White Cheddar Roasted Cauliflower Soup

This white cheddar cauliflower soup starts in the oven. Cauliflower florets roast at 425°F until their edges turn deep golden brown, which gives the soup a nutty, toasty flavor that boiled cauliflower never gets. They simmer briefly with onion, garlic, thyme, broth, and milk, then everything is blended until velvety smooth.

Two cups of freshly grated sharp white cheddar are whisked in at the very end, with the burner off and in small batches, so the soup turns creamy and cheesy instead of grainy. A light butter-and-flour roux keeps it thick enough to coat a spoon and helps the cheese melt smoothly. It makes about 8 1/2 cups, enough for 6 bowls, in a little over an hour.

Why You’ll Love This Recipe

• Real roasted flavor: Two sheet pans and a hot oven give the cauliflower room to brown instead of steam, and that browning carries through the whole pot.
• Smooth, not grainy: Freshly grated cheese, added off the heat after a splash of cold milk cools the soup, melts into a silky finish.
• Cheesy but balanced: Eight ounces of sharp white cheddar and a teaspoon of Dijon mustard give it a clear cheddar bite without hiding the cauliflower.
• Controlled salt: Low-sodium broth and seasoning at the end keep the salty cheese from taking over.
• Toppings built in: A cup of the best-browned florets is set aside before blending to scatter over each bowl.

Ingredients

Prep: 15 minutes  |  Cook: 50 minutes  |  Total: 1 hour 5 minutes  |  Yield: about 8 1/2 cups (6 servings of about 1 1/3 cups)

Equipment: 2 rimmed half-sheet pans (about 18 by 13 inches), 5- to 6-quart Dutch oven or other heavy pot, whisk, wooden spoon, immersion blender (or a countertop blender), box grater, ladle

• 1 large head cauliflower (2 1/2 to 3 pounds), trimmed and cut into 1 1/2-inch florets (about 2 pounds, or 8 cups florets)
• 3 tablespoons olive oil
• 3/4 teaspoon kosher salt, divided, plus more to taste
• 1/2 teaspoon freshly ground black pepper, divided
• 3 tablespoons unsalted butter
• 1 medium yellow onion, chopped (about 1 1/2 cups)
• 3 garlic cloves, minced
• 2 teaspoons fresh thyme leaves (or 3/4 teaspoon dried thyme)
• 3 tablespoons all-purpose flour
• 4 cups low-sodium chicken or vegetable broth
• 1 1/2 cups whole milk, divided
• 1 teaspoon Dijon mustard
• 8 ounces sharp white cheddar, freshly grated from a block (about 2 cups)
• 2 tablespoons chopped fresh chives or flat-leaf parsley

Ingredient Notes

• Cauliflower: A large head usually weighs 2 1/2 to 3 pounds and trims down to about 2 pounds of florets. Cut them about 1 1/2 inches across with at least one flat side, since flat sides brown best against the hot pan. The tender inner core can be sliced and roasted too. Expect the florets to lose roughly a quarter of their weight in the oven as water cooks off, which is why this recipe uses a full 4 cups of broth plus milk.
• Olive oil: Three tablespoons coat 2 pounds of florets well enough to brown without leaving them greasy.
• Butter and flour: Three tablespoons of each make a light roux. It adds just enough body and, more importantly, the flour’s starch helps keep the cheese smoothly emulsified in the soup.
• Onion, garlic, and thyme: They give the soup its savory base. Fresh thyme is best, but 3/4 teaspoon dried works.
• Low-sodium broth: Chicken broth gives a rounder flavor, and vegetable broth keeps the soup vegetarian. Choose low-sodium either way. Cheddar brings a lot of salt, and regular broth can make the finished soup taste too salty.
• Whole milk: One cup simmers with the cauliflower, and the last 1/2 cup goes in cold after blending to take the soup off the boil before the cheese. Lower-fat milk works, though the soup will be a little less rich.
• Sharp white cheddar: Buy an 8-ounce block and grate it yourself on the large holes of a box grater for about 2 cups. Pre-shredded bags contain added starch and cellulose to stop the shreds from sticking together, and those additives get in the way of a smooth melt, often leaving a sandy texture. Sharp or extra-sharp gives the clearest cheese flavor.
• Dijon mustard: One teaspoon doesn’t taste like mustard in the finished soup. It sharpens the cheddar flavor, the way a pinch of mustard does in mac and cheese.

How to Make White Cheddar Roasted Cauliflower Soup

1. Roast the florets: Heat the oven to 425°F with racks in the upper and lower thirds. Divide the cauliflower between 2 rimmed half-sheet pans, drizzle with the olive oil, sprinkle with 1/2 teaspoon of the kosher salt and 1/4 teaspoon of the black pepper, and toss to coat. Spread the florets in a single layer with space between them, flat sides down. Roast for 15 minutes, then toss, swap the pans between racks, and roast for 10 to 15 minutes more, until the florets are deep golden brown on the edges and flat sides and a knife slides through the thickest stems. Set aside 1 cup of the smallest, best-browned florets for topping.
2. Soften the onion: While the cauliflower roasts, set a 5- to 6-quart Dutch oven over medium heat and melt the butter. Stir in the onion with the remaining 1/4 teaspoon of kosher salt. Let it soften for 6 to 7 minutes, stirring now and then, until translucent but not browned. Add the garlic and thyme; after about 1 minute they'll smell fragrant.
3. Make the roux: Sprinkle the flour over the onion and stir constantly for 2 minutes, until no dry flour remains and it smells lightly toasted.
4. Add the liquids: Slowly pour in the broth while whisking to keep lumps from forming, then whisk in 1 cup of the milk. Add the roasted cauliflower (not the reserved florets) and the remaining 1/4 teaspoon of black pepper, scraping the pan into the pot.
5. Simmer: Bring to a simmer over medium heat, then lower the heat and simmer gently with the lid slightly ajar for 10 minutes, stirring now and then, until the cauliflower is very soft and the soup has thickened slightly.
6. Blend until smooth: Turn off the heat. Blend with an immersion blender for 2 to 3 minutes, until completely smooth. If using a countertop blender, work in batches, fill the jar no more than halfway, remove the center cap from the lid, and cover the opening with a folded towel while blending. Return the soup to the pot.
7. Cool it slightly and add the mustard: With the heat still off, whisk in the remaining 1/2 cup of cold milk and the Dijon mustard. The soup should be steaming but no longer bubbling.
8. Melt in the cheddar: Add the cheddar in 4 handfuls, whisking after each one until it has melted before adding the next. If the last handful won't melt, set the pot over the lowest heat and whisk just until smooth. Don't let the soup bubble once the cheese is in.
9. Season and serve: Taste and add more kosher salt, a pinch at a time, only if needed. Ladle into bowls and top with the reserved roasted florets and the chives.

Tips for Success

• Give the cauliflower room. Crowded florets trap steam and turn pale and soft. Two pans with space between the pieces give you real browning, and browning is where the flavor comes from. Look for deep golden edges and a few darker tips, not just a light tan.
• Keep the soup below a simmer once the cheese goes in. Cheddar is an emulsion of fat, water, and milk proteins. Too much heat makes the proteins tighten into tiny curds and squeeze out the fat, which is what makes cheese soups grainy or oily. Turning off the heat, adding cold milk, and melting the cheese gradually keeps the temperature gentle. The starch from the roux coats the melting cheese and helps it stay smooth.
• Grate the cheese yourself. A block of cheddar melts far more smoothly than bagged shreds, which carry anti-caking agents.
• Blend before the cheese. Blending a hot, cheesy soup at high speed can overheat the cheese. Blend the cauliflower base first, then add the cheese by hand.
• Salt at the very end. Broth, cheese, and the roasted cauliflower all add salt. Taste only after the cheese has melted.

Variations and Substitutions

• Without the cheese: For a plain roasted cauliflower soup, skip the cheddar and mustard, add an extra 1/2 cup of milk, and finish with a squeeze of lemon and a drizzle of good olive oil. Season it a little more, since there’s no salty cheese.
• Roasted garlic: Roast 4 unpeeled garlic cloves on one of the pans, squeeze them out of their skins, and add them with the cauliflower for a mellower, sweeter garlic flavor.
• Smoky finish: Dust each bowl with a pinch of smoked paprika, or top with crumbled crisp bacon.
• Yellow cheddar or a blend: Sharp yellow cheddar tastes the same and turns the soup golden orange. Up to 2 ounces of the cheddar can be swapped for Gruyere for a nuttier flavor.
• Gluten-free: Skip the flour and simmer 1 medium Yukon Gold potato, peeled and diced, with the cauliflower. The blended potato thickens the soup instead of the roux. Melt the cheese very gently, since there’s no flour to help stabilize it.
• Richer: Replace 1/2 cup of the milk with heavy cream.

What to Serve with Cauliflower Cheese Soup

Serve bowls with crusty bread, garlic toast, or a grilled cheese sandwich for dipping, or top with buttery croutons. A crisp green salad or sliced apples balance the richness.

Craving another cheese-forward bowl? Make our sharp cheddar mac and cheese soup with crispy bacon, or pair broccoli and cheddar in our creamy broccoli cheddar gnocchi soup. Our fall soup recipes list has dozens more seasonal ideas, and every soup on the site is gathered in our soup recipes category.

Storage, Reheating, and Freezing

• Refrigerate: Get leftovers into covered containers and into the refrigerator within 2 hours of cooking. They’ll keep for 3 to 4 days, and the soup thickens as it chills.
• Reheat: Rewarm it slowly in a saucepan over low heat, stirring frequently and loosening it with a little milk or broth, until it’s steaming hot (165°F). Don’t let it boil, or the cheese can separate. In the microwave, heat single portions at 50 percent power, stirring every minute.
• Freezing: Once the cheese is in, this soup freezes poorly. Dairy-rich cheese soups often turn grainy or separate after thawing. If you want to freeze some, ladle out portions after blending (step 6) but before adding the last of the milk and the cheese, and freeze for up to 3 months. Thaw overnight in the refrigerator, whisk or blend it smooth as it warms, then take it off the heat and melt in about 1 ounce (1/4 cup) of grated cheddar per cup of soup.
• Make ahead: The roasted cauliflower can be made 2 days in advance and chilled. Then make the soup as written, allowing a few extra minutes for it to come to a simmer.

White Cheddar Cauliflower Soup FAQ

Why did my cheese soup turn grainy?

Usually the soup was too hot when the cheese went in, or it boiled afterward. Pre-shredded cheese can also make it gritty. Add freshly grated cheese off the heat in small handfuls, and warm leftovers gently without boiling.

Can I use pre-shredded cheddar?

It’s better not to. The starches and cellulose that keep bagged shreds from clumping also keep them from melting smoothly. A block of sharp white cheddar gives a creamier soup.

Should I roast or boil the cauliflower for soup?

Roasting gives far more flavor. Boiled cauliflower makes a mild, slightly cabbage-like soup, while roasted cauliflower adds nutty, caramelized notes. The roasting takes about 30 minutes, and you can make the soup base while it’s in the oven.

How much cheese goes in cauliflower cheese soup?

This recipe uses 8 ounces of sharp white cheddar, about 2 cups freshly grated, for about 8 1/2 cups of soup. That gives a clear cheese flavor without making the soup heavy.

Can you freeze cauliflower cheese soup?

Not well once the cheese is added, since it tends to turn grainy. Freeze the blended base before the cheese instead, then melt the cheese in after reheating.

How can I adjust the thickness of the soup?

To thin it, whisk in warm broth or milk a few tablespoons at a time. To thicken it, simmer the blended base uncovered for a few minutes before adding the last of the milk and the cheese, since reducing it after the cheese goes in risks graininess.

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