Roasted butternut squash soup gets its depth from the oven: cubes of squash, onion, a tart apple and whole garlic cloves roast until their edges caramelize, then simmer briefly in broth and get blended until silky. A spoonful of brown butter with crisp sage goes on top. It takes about 80 minutes, and the oven does most of the work.
Why roast the squash instead of boiling it?
Boiled squash tastes like squash and water. It soaks up liquid as it cooks, and the soup ends up thin, pale and mildly sweet, which is why so many recipes lean on a lot of cream. Roasting does the opposite. In a hot oven, the squash loses water and concentrates, and the sugars on its cut faces brown into something closer to caramel and toasted nuts.
Those browned edges are what you're after, so give them room. Spread the cubes across two sheet pans in a single layer with space between pieces. Crowded on one pan, they release steam faster than it can escape and turn soft without ever coloring. Flip them halfway and swap the pans between racks so both trays brown evenly.
The onion, apple and garlic roast alongside for the same reason. Raw onion simmered in broth tastes sharp and vegetal, but roasted wedges add a sweetness that's mellow and round. Garlic cloves roasted in their skins turn soft and jammy, and they squeeze right out into the pot.
Halved vs cubed squash: which roast makes better soup?
Both work. The choice comes down to how much browning you want and how you feel about peeling. Cubes give the deepest flavor; halves are easier when your knife is dull or your squash is huge.
| Method | Oven | Time | Result |
|---|---|---|---|
| 1 inch cubes, peeled | 425°F (220°C) | 35 to 40 minutes | Browned edges, the richest, most caramelized soup |
| Halves, cut side down | 400°F (200°C) | 45 to 60 minutes | Soft and sweet, little browning, no peeling |
| Halves, cut side up | 400°F (200°C) | 50 to 60 minutes | Some browning on the rim, drier flesh |
If you roast halves, brush the cut faces with oil and season them before they go in. Scoop the flesh out once a knife slides through the neck with no resistance, and add the browned bits from the sheet pan too. Expect a slightly lighter, sweeter soup, so you may want the full 2 teaspoons of vinegar at the end.
Peeling and cutting a butternut squash safely
A butternut squash is hard, round and slippery, which is a bad combination for a knife. The goal is to give it flat sides to rest on before you cut anything thick.
- Microwave the whole squash for 2 to 3 minutes, after poking it a few times with a fork. The skin softens enough to peel more easily.
- Trim 1/4 inch off the top and bottom so the squash stands steady.
- Cut it crosswise where the narrow neck meets the round bulb. You now have two shorter, more stable pieces.
- Stand each piece on a flat end and peel down the sides with a sharp Y peeler, going deep enough to remove the pale green layer under the skin.
- Halve the bulb and scoop out the seeds and stringy fibers with a metal spoon.
- Cut everything into 1/2 inch slabs, then into 1 inch cubes.
A 3 1/2 pound squash gives about 9 cups of cubes. The same technique works for the squash in an autumn harvest salad, so it's worth cutting extra and roasting a second tray.
How thick should roasted butternut squash soup be?
It should coat a spoon and slowly fall off it, closer to heavy cream than to porridge. Squash varies a lot in water content, so the exact amount of broth changes from one squash to the next. Start with 4 cups, blend, and then thin it with more broth, 1/4 cup at a time, until it pours from the ladle in a thick ribbon.
A countertop blender gives the smoothest, most velvety result. Hot soup expands in a blender, though, and steam can blow the lid off. Fill the jar no more than halfway, remove the center cap from the lid, cover the hole with a folded towel and start on the lowest speed before working up to high. Blend each batch for a full minute or more.
An immersion blender is easier and safer, and it saves washing a jar. The soup won't get quite as silky, but it'll be close. Keep the blade fully under the surface and tilt the pot slightly so it stays deep enough. If you still see flecks of onion or apple after 2 minutes, push the soup through a fine sieve.
Does the soup need cream?
Not really. Roasted squash blends up creamy on its own, and the soup is rich enough without any dairy. Cream softens the flavor and makes it a little more luxurious; leave it out and the roasted, slightly savory taste comes through more clearly.
- Heavy cream: 1/2 cup stirred in after blending. Smooth and mellow.
- Full fat coconut milk: 1/2 cup. Silky, with a faint coconut note that suits a pinch of curry powder.
- Crème fraîche or Greek yogurt: a spoonful swirled into each bowl, for tang instead of richness.
- Nothing at all: add an extra tablespoon of olive oil to the roasting pan.
The brown butter sage is worth the 3 minutes. The butter turns nutty, the sage leaves crisp up like chips, and both cut through the sweetness of the squash. Pair a bowl with a grilled cheese made on sourdough bread, or start a fall dinner with small cups before a tray of oven roasted root vegetables.
The recipe
Roasted Butternut Squash Soup with Apple and Brown Butter Sage
Ingredients
For the soup
- 1 large butternut squash (about 3 1/2 pounds / 1.6 kg), peeled, seeded and cut into 1 inch (2.5 cm) cubes, about 9 cups
- 1 medium yellow onion, cut into 8 wedges
- 1 tart apple (Granny Smith or Honeycrisp), peeled, cored and quartered
- 4 garlic cloves, unpeeled
- 3 tablespoons olive oil
- 1 1/2 teaspoons kosher salt, plus more to taste
- 1/2 teaspoon freshly ground black pepper
- 4 cups (950 ml) low sodium vegetable or chicken broth, plus more to thin
- 1/4 teaspoon freshly grated nutmeg
- 1/2 cup (120 ml) heavy cream or full fat coconut milk (optional)
- 1 to 2 teaspoons apple cider vinegar
For the brown butter sage
- 3 tablespoons (40 g) unsalted butter
- 12 fresh sage leaves
- 2 tablespoons toasted pepitas (pumpkin seeds)
Instructions
- Heat the oven. Heat the oven to 425°F (220°C) with racks in the upper and lower thirds. Line two rimmed sheet pans with parchment paper.
- Season the vegetables. Toss the squash, onion, apple and garlic cloves with the olive oil, salt and pepper. Spread them in a single layer across both pans, leaving space between the pieces.
- Roast until browned. Roast for 35 to 40 minutes, flipping the pieces and swapping the pans between racks halfway, until the squash is soft all the way through and deeply browned at the edges.
- Simmer with broth. Squeeze the garlic out of its skins into a large pot. Add the roasted vegetables, the broth and the nutmeg, bring to a simmer over medium heat and cook for 10 minutes.
- Blend until silky. Blend in batches, filling the blender no more than halfway with the lid vented and covered with a towel, or use an immersion blender, for 1 to 2 minutes until completely smooth. Return to the pot, stir in the cream if using and thin with more broth until it pours in a thick ribbon.
- Brown the butter. Melt the butter in a small skillet over medium heat. Add the sage leaves and cook for 2 to 3 minutes, swirling, until the butter smells nutty and turns golden brown and the leaves are crisp.
- Season and serve. Stir 1 teaspoon of vinegar into the soup, taste, and add more vinegar and salt until it tastes bright. Ladle into bowls and top with a drizzle of brown butter, the crisp sage leaves and the pepitas.
Cook's notes
- The soup keeps for 3 to 4 days in the fridge and thickens as it chills; thin it with broth when you reheat it.
- For the freezer, hold back the cream, freeze the soup for up to 3 months, and stir the cream in after reheating.
- Make it vegan by using vegetable broth and coconut milk and frying the sage in olive oil instead of butter.
- A pinch of cayenne or 1/2 teaspoon of curry powder added with the nutmeg gives the soup gentle heat.
Roasted Butternut Squash Soup questions
Why does my butternut squash soup taste flat?
It usually needs salt, acid or both. Squash is sweet and mild, and without enough of either the soup tastes like baby food. Add salt a pinch at a time, then stir in 1 teaspoon of cider vinegar or lemon juice and taste again. Pale, unbrowned squash also tastes flat, so roast until the edges are clearly caramelized.
Is butternut squash soup vegan?
It can be with three small swaps. Use vegetable broth instead of chicken broth, choose full fat coconut milk instead of heavy cream, and fry the sage leaves in olive oil rather than butter. The roasted squash, apple, onion and garlic carry most of the flavor, so the vegan version stays rich, smooth and deeply savory.
What other squash can I use for this soup?
Kabocha is the best swap. It's drier and nuttier than butternut and roasts beautifully, though its skin is tough enough that halving it is easier than peeling. Sugar pie pumpkins work well too. Acorn squash is milder and a little stringy, so blend it longer. Use the same weight of any of them, about 3 1/2 pounds.
How long does squash soup keep in the freezer?
About 3 months in airtight containers with an inch of headspace for expansion. Freeze it before adding cream, because dairy can separate and turn grainy once thawed. Thaw the soup overnight in the fridge, reheat it gently over medium low heat, then stir in the cream and a splash of broth and check the salt and vinegar again.
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