Caramelized Onion Butternut Squash Soup

This creamy butternut squash soup has a unique depth of flavor that comes from slowly caramelizing the onions. This soup comes together quickly in an Instant Pot, or you can make it on the stovetop. It contains bone broth for added protein and extra healing power, not to mention it is Whole30 compliant, paleo, and made with 100% real whole foods.

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A bowl of creamy Caramelized Onion Butternut Squash Soup on a cream plate with a baguette and silver spoon on the side.

There are thousands of butternut squash soup recipes out there, but sometimes it’s just best to keep things simple. This Caramelized Onion Butternut Squash Soup has a minimal ingredient list, but that doesn’t mean it is bland or lacking in the flavor department. Only 8 common ingredients are needed to make this soup and the only spices used are salt and pepper. There is no fruit or sugar added to sweeten this soup-the sweetness is brought out by caramelizing the onion which compliments the squash nicely. This allows the flavor of each ingredient to shine and creates a harmonious soup that is simple yet delicious.

Next to a window, someone is holding one half of a butternut squash and scooping out the seeds.

HOW TO PREPARE BUTTERNUT SQUASH FOR SOUP

The hardest part of making butternut squash soup from scratch is cutting up the butternut squash. They are often dense so require some muscle work and serious elbow grease when preparing. However, don’t be tempted to skip this step by opting for those “convenient” pre-cut bags of butternut squash. Their flavor can’t compare with the fresh taste and sense of pride that come with cutting your own.

When cutting any fruit or vegetable that is dense and fairly large, it is easier and safer when you have the right kitchen gear. To prepare butternut squash, you will need a medium to a large cutting board that doesn’t move around, a sharp heavy-duty knife, a vegetable peeler, and a spoon. Make sure your knife is sturdy and well-balanced as it really will make a difference.

I like to slice the butternut squash in half lengthwise before peeling it. This is because underneath it’s outer layer the squash is quite slippery, and you’ll want to be able to get a firm grip to cut it safely. Next, take a spoon, scoop out the seeds, and discard. Now I take a vegetable peeler, peel the skin off, and discard. Finally, slice the squash into 1 ½ inch thick slices and then into 1 ½ inch cubes.

On a marble background, a butternut squash is being prepared. It has already been cut in half, peeled, some of the seeds have been scooped out, and it has been cut into cubes. The squash is on a wood cutting board and there is a spoon next to it.

A wood cutting board with diced vegetables is sitting on a marble counter. There is a knife and celery, carrot, and garlic is being cut into small pieces.

HOW TO MAKE BUTTERNUT SQUASH SOUP FROM SCRATCH

When making butternut squash soup from scratch, start with sourcing the freshest, highest-quality ingredients. Because this recipe has such a minimal ingredient list, everything counts.

Next up is the base of the soup. For this recipe and every soup I make, I use bone broth. You can use beef, pork, or chicken bone broth. I have two separate posts here and here if you're interested in making it homemade. It is an essential ingredient to my soup recipes because it makes them richer and more nourishing, it’s also an excellent way to add some protein to this otherwise vegetarian soup.

Whether you make your bone broth or buy it from the store, check to see if it contains collagen and gelatin. The gelatinous kind of pre-made bone broth is stored in the refrigerated or freezer section of the grocery store. You will also want to buy one that is neutral in flavor and is either low in salt or has no salt added so that you can control the seasonings yourself. I strongly advise against using bouillon cubes or a carton of stock or broth. The recipe will not turn out the same and it does make a difference in the flavor and consistency of the soup!

Now you’re ready to make soup! Start by caramelizing the onion. This process should not be skipped and cannot be rushed. It does take between 45-60 minutes to properly caramelize the onions, but you can step away occasionally to do other tasks while you’re waiting. Just stir occasionally to prevent burning.

Caramelizing the onions is essential because it adds a natural sweetness to the soup without added sugar or extra ingredients. Cooking them low and slow will release the natural sugars from the onions, which adds depth and richness to this soup. You know they're ready when they appear a golden brown color and look stringy, almost mushy.

A collage of process photos showing the steps to making butternut squash soup from scratch. There is a photo of onions being caramelized, carrot and celery being sauteed, and the soup being pureed using an immersion blender.

Once the onions are done caramelizing, add the garlic, carrots, and celery. You will sauté that for 3-4 minutes, then add the broth and cubed butternut squash. Whether you're cooking this soup on the stovetop or in the Instant Pot, cook until the squash is very soft and tender. Then puree using your preferred kitchen appliance.

I’ve used a food processor, immersion blender, and blender before and they all will get the job done. However, I do find that a high-speed blender such as a Vitamix will result in a creamier soup. Do be careful though, I’ve had hot soup explosions before and they are not fun. To prevent this from happening, puree in batches. Fill the container with soup making sure you don’t go above the halfway point. Secure the lid without the plastic middle piece and place a clean kitchen towel on top. Blend until smooth and with the power still on, carefully take the towel off and add more soup through the open hole until you reach 1-2 inches below the max fill line. Repeat this process until all the soup is pureed.

After you have pureed the soup, transfer it back into the pot or Instant Pot and simmer until it has thickened a little. This takes between 10-30 minutes depending on what device you use and how thick you like your soup. This last step will mellow out all the flavors and bring everything together.

Last up is seasoning the soup! Flavor with pepper and salt to taste, I recommend 1/4 a teaspoon of pepper if you don’t want it very spicy or 1/2 a teaspoon if you want a little kick. Finding the sweet spot when it comes to salt is is the final stretch to making this soup. I use a fine grain pink Himalayan salt and usually start with 1 teaspoon and add more salt in increments of 1/4 a teaspoon until it the soup taste right!

A tablescape photo showing three bowls of instant pot butternut squash soup, wine, and bread ready to be consumed.

WHAT GOES WELL WITH BUTTERNUT SQUASH SOUP

This soup can be a balanced meal on its own because of the protein from the bone broth and multiple vegetables, but if you’re wanting more sustenance, a salad, and some fresh sourdough bread pairs perfectly with butternut squash soup!

For a weeknight dinner, make a simple salad with some fresh greens, topped with olive oil and vinegar. If you are wanting a more elaborate salad to spice things up or to serve to guests, my Kale, Asian Pear, and Fennel Salad complements this simple soup nicely.

Another great pairing for this soup is a fresh loaf of sourdough bread from the local bakery or grocery store, slathered of course with some Irish butter. Yum! Choosing to serve this with bread on the side will give you a cozy, hearty, well-balanced meal! I’m feeling warming already and am ready to face this winter.

A zoomed in photo of the butternut squash soup showing the luscious consistency. The soup is topped with a drizzle of olive oil, extra caramelized onions, and fresh cracked pepper.

A tablescape photo showing two bowls of instant pot butternut squash soup, wine, bread, and butter ready to be consumed.

I hope you enjoy this recipe! If you need any help, feel free to leave me a comment or send me an email. Happy cooking!

instant pot butternut squash soup, Caramelized onion butternut squash soup,Easy butternut squash soup recipe

Soup, Broth

American

Yield: 4

Author: Paige McDonald