This Low Carb Butternut Squash Soup Recipe is truly delightful. Roasted butternut squash and cauliflower in a creamy broth packed with fresh herbs, onion, and garlic. This rich, comforting soup is full of flavor, with fewer carbs so it's the perfect lunch side on the keto diet.
You're going to love how simple this soup is to make. We do recommend roasting the squash and cauliflower first (thank us later), but it's not 100% necessary. Either way, the prep time is super minimal. This soup is incredibly rich and creamy, and just the ultimate cool weather soup.
Full quantities and nutritional information are located in the recipe card.
- Butter & olive oil- We use olive oil to roast the squash and cauliflower since it can withstand higher temperatures than butter. Butter adds a rich creaminess to the soup that is simply delicious.
- Butternut squash - You can buy butternut squash peeled and already chopped into small pieces, and that would be a super easy route to take. Otherwise, just carefully cut a medium squash in half lengthwise and scoop out the seeds and "guts" and discard. You can also save the seeds and roast them to top the soup!
- Cauliflower- Cauliflower is so neutral in flavor alongside the squash, it really allows the squash to shine, but it also cuts down on the carbs in the soup. You can use fresh or frozen cauliflower here. You will need about a pound /16 ounces/ 448 grams of cauliflower.
- Onion & garlic - The base of anything savory and delicious. You can substitute garlic and onion powder if you prefer.
- Fresh thyme & sage - For an incredibly lovely flavor. Again, this can be substituted for dried herbs as well.
- Dry seasonings - Kosher salt, black pepper, smoked paprika, red pepper flakes and nutmeg are all we used in the dried seasonings section. Red pepper flakes add a subtle heat, smoked paprika adds some smokiness, and nutmeg is a must try, as it adds a lovely warmth to the soup. Of course, season to taste and if you don't like something, feel free to leave it out.
- Broth - We find that using chicken bone broth adds a ton of flavor, nutrients and protein, so we often opt for that. That being said, any vegetable or chicken broth or stock will work perfectly fine here.
- Heavy cream - Added near the end for a really great creaminess. You could use half and half if you prefer, or your favorite dairy free milk or cream option.
- Garnish with - fresh thyme, heavy cream, black pepper, fried sage leaves, sour cream, olive oil (optional)
Roast cauliflower & butternut squash
Cut the cauliflower into large chunks, and cut the butternut squash in half lengthwise, cleaning out the seeds. Preheat the oven to 400°F. Prepare two large baking sheets with parchment paper.
Add cauliflower and butternut squash to the baking sheets, and coat with olive oil, then season generously with salt and pepper. Roast until golden brown and fork tender, about 35-45 minutes, tossing halfway through.
Toast the aromatics
Meanwhile, in a large stock pot or dutch oven, melt the butter over medium heat. Add in onion, with a pinch of salt and cook until softened and translucent, about 5-7 minutes.
Once softened, add in fresh herbs, spices and garlic, and cook until garlic is fragrant, about 30 seconds.
Add roasted veggies & broth
Add in the roasted cauliflower and squash, then pour in stock and simmer for 10-15 minutes.
Add heavy cream & adjust seasonings
After 15 minutes, stir in heavy cream to warm through. Adjust seasonings to taste.
Puree, garnish & serve!
Transfer soup mixture to a blender or use an immersion blender to puree the soup.
Once smooth, ladle into bowls and garnish with sour cream or heavy cream, salt, pepper, and herbs. *For an extra special flavor, fry a few pieces of sage in some olive oil on the stovetop for garnishes.
✨Tips & tricks
Here are out top tips to ensure you get the best roasted butternut squash soup every time!
- To avoid roasting the vegetables (if you must!) then boil the cauliflower and butternut squash with the broth, and simmer for 20-30 minutes until softened.
- Although we do recommend using fresh garlic, sage, and thyme, you can substitute for dried spices instead.
💭Frequently asked questions
While we haven't tried these substitutes ourselves, these are pretty simple swaps to fit any diet.
For dairy free - simply substitute the butter for all olive oil, or your favorite butter substitute. You will also need to replace the heavy cream with your favorite dairy free replacement, like full-fat, unsweetened coconut milk (that comes in a can).
For vegetarian or vegan, replace all dairy elements as mentioned above, and also make sure to use vegetable broth instead of chicken broth.
Yes, definitely, in small portions, this butternut squash soup is totally keto friendly.
Everyone is different, ketosis is a metabolic state, not a food.
Butternut squash soup is quite a starchy vegetable, so keep this in mind. The portion sizes are on the small side, making it a perfect side to a protein heavy meal. There are 9 net carbs per serving, so we think it can totally fit into your way of eating.
🍅More recipes to try
- Keto 'Potato' Soup (Super Loaded!) (made with turnips)
- Keto Candied Butternut Squash
- 'Potato' Leek Kale Soup (made with turnips)
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🥣Storage & reheating
- Fridge: Store in an airtight container in the fridge for up to 5 days.
- Freezing: To freeze, allow to cool to room temperature completely. Store in an airtight, freezer-safe container for up to 6 months.
Reheat gently on the stovetop, being mindful not to let the soup boil. The heavy cream can curdle if the cream becomes too hot. You can also reheat gently in the microwave at 50% power.
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Keto Butternut Squash Soup
- 1 medium butternut squash, halved lengthwise, seeds removed
- 1 head cauliflower, cut into pieces
- 3 tablespoons olive oil
- 1 tablespoon kosher salt, divided
- 1.5 teaspoons black pepper
- 3 tablepsoons unsalted butter
- 1 medium yellow onion, diced
- 6 cloves garlic, minced
- 2 tablespoons fresh sage, minced
- 2 tablespoons fresh thyme leaves
- 1 teaspoon smoked paprika
- ½ teaspoon red pepper flakes
- ½ teaspoon ground nutmeg
- 4 cups chicken broth
- 1 cup heavy whipping cream
- Preheat the oven to 400°F. Prepare two large baking sheets with parchment paper. Add cauliflower and butternut squash to the baking sheets, and coat with olive oil, then season generously with salt and pepper. Roast until golden brown and fork tender, about 35-45 minutes, tossing halfway through.
- Meanwhile, in a large stock pot or dutch oven, melt the butter over medium heat. Add in onion, with a pinch of salt and cook until softened and translucent, about 5-7 minutes. Once softened, add in fresh herbs, spices and garlic, and cook until garlic is fragrant, about 30 seconds.
- Add in the roasted cauliflower and squash, then pour in stock and simmer for 10-15 minutes. After 15 minutes, stir in heavy cream to warm through. Adjust seasonings to taste.
- Transfer soup mixture to a blender or use an immersion blender to puree the soup. Once smooth, ladle into bowls and garnish with sour cream or heavy cream, salt, pepper, and herbs. *For an extra special flavor, fry a few pieces of sage in some olive oil on the stovetop for garnishes.
- Store in an airtight container in the fridge for up to 5 days. Gently simmer on the stovetop or reheat gently in the microwave to warm up.
- Butternut squash is a naturally starchy vegetable, so the serving sizes are small. This soup is perfect as a side to any meal.
- Season to taste, and feel free to substitute fresh herbs with dried herbs, a good rule of thumb is to use about ⅓ of the amount of dried as you would use fresh. So in this case, use about 2 teaspoons of fresh thyme and 2 teaspoons of fresh sage in place of 2 tablespoons each of fresh.
- Smoked paprika and red pepper flakes are optional.
- Garlic powder and onion powder can be substituted for fresh onion and garlic.
- If you don't wish to roast the squash and cauliflower beforehand, you can always simmer them in the broth alongside the aromatics instead. Simmer until veggies are nice and soft, about 20-30 minutes, then puree as normal before serving. We do highly recommend roasting the veggies if you get the chance! It really deepens the flavor of this soup.