Sweet Potato Butternut Soufflé

Kirstin, It's Not You, It's Brie

Sweet potatoes, butternut squash and brown butter have always been food pairing buddies. Add leeks and sweet and buttery semi-soft Alpine-style cheese to them, and you’ve got a rich Thanksgiving dish that could knock Aunt Lola’s sweet-potato marshmallow casserole out of the water (better set them on different ends of the table so Lola doesn’t hear them compared much).

This dish is a casserole-soufflé hybrid that’s rich and fluffy. It’s especially good with Brussels sprout salad a couple days after Thanksgiving.

Sweet Potato Butternut Soufflé
By Kirstin
Serves 4-6


3 ½ tablespoons salted butter, divided
1 ½ pound butternut squash, cut in half lengthwise and seeds removed
¾ pound sweet potato
1 ½ pounds leek, untrimmed
½ teaspoon salt
pinch cardamom
pinch nutmeg
4 ounces (½ cup) Alpine-style cheese (such as Gruyere or Swiss), shredded
2 eggs, beaten
¼ teaspoon ground pepper


Preheat oven to 350°F.

Add ½ tablespoon butter to a rimmed baking sheet and place in oven on lower rack. Season the inside of the squash with salt and pepper. Once the butter is melted, lay the squash facedown on the buttered tray and return to the oven. Pierce the sweet potatoes with a fork 6 times and add them to the oven, resting directly on the upper rack. Cook both until pierced easily with a fork, 45 minutes to 1 hour for the squash, and 30-45 minutes for the sweet potato.

While the squash and potatoes cook, slice off the bottom of the leeks. Cut off and discard the top dark green part and the roots. Slice the remaining leek lengthwise, then width-wise, ½-inch thick. Wash well under running water to rid the leek of any debris.

Melt 2 ½ tablespoons butter in a medium-sized sauté pan and melt over medium heat. Scraping the bottom of the pan for about 3-5 minutes, cook until the butter turns light brown. If butter foams while browning, take off heat and stir until foam subsides, then return to heat until the butter is walnut-hued. Add the leeks, ¼ teaspoon salt, cardamom and nutmeg, and cook for 10 minutes. Set aside.

Once squash and potatoes are cooked and cool enough to touch, scrape out their interiors (discard the skins) and run through a food mill or processor into a large bowl. Add the leeks and browned-butter mixture, grated cheese, eggs, ¼ teaspoon salt and ground pepper. Mix well. Spoon into a heavy-bottomed 8 x 8 buttered (using remaining ½ tablespoon butter) baking dish and bake for 20-30 minutes, until the top turns golden. Cool for 5 minutes and serve.

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  1. Den said:

    This Sweet potato and squash recipe looked good, also the Roasted balsamic onions. I could make those to bring up on our Xmas wknd visit, the 21st. Had you asked dan and Ann?