Roasted Cauliflower Onion Soup

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Creamy…and cheesy with a roasted boldness and a hint of fresh thyme. Mmmm.  This roasted cauliflower onion soup warms you up on a cold day.

But, it doesn’t have to be cold outside. (Have I mentioned I live in Florida?) Although cauliflower is considered a fall/winter vegetable, it is plentiful year round. I’ve been on a bit of a winter soup kick ever since I posted the Butternut Squash Bisque recipe.

Roasted Cauliflower Onion Soup in a bowl

I used low-fat cheese which made this low in points and calories.

A word on size before we move through this adventure. The size of a cauliflower head can vary widely. The one I used was medium-sized. If the one you end up using is larger, then you may want to add a little more broth. More or less broth…it really tastes great either way.

 Chopped cauliflower and onions on a cutting board

Cut 1 head of cauliflower into similar sized pieces and cut a large onion into small pieces. (I sliced it into rings and then cut the rings into fourths.) There is no need to be fanatical about the size of the pieces, but pieces of the same size will cook more evenly. Toss the cauliflower and onion mixture with olive oil, salt and pepper and roast in a 400 degree Fahrenheit oven for about 2o to 25 minutes or until…

Roasted cauliflower and onion

the cauliflower and onion are slightly browned.

Prepare fresh thyme

While the roasting is going on, prep the thyme. Gently slide fingers down the stem in the direction that is opposite of how the leaves grow. (I love fresh thyme because it so easy…no chopping is necessary because the leaves are so small.) You need about 1 teaspoon.  If you don’t have fresh thyme, then use about 1/4 teaspoon of dried.

Garlic being pressed through a garlic press into a pot

Saute 2 cloves of garlic and the thyme for a few minutes in olive oil until they are fragrant. (Love my garlic press. No mess!)

Roasted cauliflower and onion soup in a pot

Add 2 cups of low-sodium chicken broth to just cover the cauliflower and onion, bring to a boil and then to turn the heat to low and simmer for about 15 to 20 minutes.

At this point, you can add a little more broth if you like your soup a little thinner or if you used a large head of cauliflower.

Cauliflower soup being pureed with a stick blender

Once everything is nice and soft (i.e., you can break things up with a spoon,)  puree the mixture with a stick blender. (Yes, you can transfer the mixture to a food processor in batches. But, I highly recommend a stick blender if you make a lot of soup.) I like my soup a little chunky, but you can make it as smooth as you like.

Add shredded sharp cheddar cheese and half and half to the pot and stir until everything is melted and combined. A sharp cheese pairs nicely with cauliflower. I’ve tried milder versions and it’s not quite as good.

The roasted cauliflower and onion mixture simmered in broth tastes wonderful. You don’t need to add anything else. I take some out at this point for my darling daughter with allergies. A little rice milk is a nice addition and we are experimenting with nutritional yeast flakes.

Roasted Cauliflower and Onion Soup

Two bowls of roasted cauliflower and onion soup…it makes about 4 cups and I have some small containers in my freezer.

If you don’t follow the vegan path described above, then it will look like this. Cheesy, creamy with bits of brown from the roasting process.

Roasted Cauliflower Onion Soup

Roasted cauliflower and onion shine in this creamy, cheesy soup. Use low-fat cheese for low points without sacrificing taste.
Prep Time15 mins
Cook Time37 mins
Course: Soup
Cuisine: American
Servings: 4 cups
Calories: 219


  • 1 head of cauliflower medium-sized
  • 1/2 large onion
  • 4 teaspoons olive oil separated into 1 Tablespoon and 1 teaspoon
  • Salt
  • Pepper
  • 2 cloves garlic pressed
  • 1 teaspoon fresh thyme 1/4 teaspoon dried
  • 2 cups low-sodium vegetable broth or chicken broth
  • 1 cup sharp cheddar cheese shredded
  • 1/2 cup milk


  • Preheat oven to 400 degrees Fahrenheit.
  • Cut cauliflower into similar sized pieces.
  • Chop onion into rings and then cut into fourths.
  • Toss cauliflower and onion with 1 Tablespoon olive oil.
  • Sprinkle with salt and pepper.
  • Roast in oven for about 20-25 minutes. Vegetables will begin to brown on the edges.
  • Cook the garlic and thyme over medium heat for 2-3 minutes or until fragrant.
  • Add roasted cauliflower and onion to garlic and thyme mixture.
  • Add 2 cups of vegetable or chicken broth.
  • Turn heat to high until mixture boils then reduce and simmer for about 15-20 minutes.
  • Remove from heat and puree mixture with a stick blender. Or transfer to a food processor in batches.
  • Stir in cheese and milk.


Vegan and allergy friendly tips: use vegetable broth and leave out cheese. Add rice milk or soy milk instead. Freezing tips: store up to 2 months in freezer.


Calories: 219kcal | Carbohydrates: 13g | Protein: 11g | Fat: 15g | Saturated Fat: 7g | Cholesterol: 33mg | Sodium: 704mg | Potassium: 537mg | Fiber: 3g | Sugar: 6g | Vitamin A: 605IU | Vitamin C: 74.6mg | Calcium: 277mg | Iron: 0.9mg
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