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Butternut Squash Gratin with Onions

  • Author: Tessa
  • Total Time: 1 hour 45 mins
  • Yield: 4 entree servings 1x


If you can’t find butternut squash, try this with pumpkin, acorn squash, or another winter squash variety. It comes together rather quickly, then slowly bakes to bubbly, cheesy, crispy perfection.


  • 1 t butter
  • 5 T olive oil, divided
  • 2 medium yellow onions, thinly sliced (4 C)
  • 1/2 t dried thyme
  • 1 1/2 t dried sage
  • 1/2 t sea salt, plus more for final seasoning
  • Ground black or white pepper
  • 6 C 1/2″ butternut squash cubes (peeled)
  • 1/3 C flour
  • 2 T chopped parsley
  • 3/4 C grated Gruyere (or fontina) cheese
  • 1/2 C + 2 T warmed whole milk
  • 1 C fresh bread crumbs (from sturdy white bread, crusts removed)


  1. Lightly butter a 2 quart gratin or other baking dish. Heat 2 tablespoons of oil in a large skillet over medium heat, then add onions and dried herbs. Cook, stirring frequently and adjusting heat to maintain a moderate sizzle. After 15 minutes, when onions are darkened, reduced in volume, and become slightly jam-like, spread in bottom of prepared dish.
  2. Preheat oven to 350 degrees.
  3. In a large mixing bowl, toss squash with flour to coat. Heat 2 more tablespoons oil in the same skillet over medium, then add squash, after shaking off excess flour, and stir immediately to coat with oil. Cook, stirring often, 7 to 8 minutes, until just starting to brown. Add parsley and sprinkle liberally with salt and pepper, then cook one more minute. If lots of flour has stuck to the pan and browned, increase heat slightly, add a couple tablespoons of water, and scrape the bottom to deglaze the pan. Include browned bits and layer the squash over the onions.
  4. Sprinkle cheese over the vegetables, the pour milk evenly over everything. Cover and bake 25 minutes.
  5. Meanwhile, mix bread crumbs with a teaspoon or so of remaining olive oil and mix to combine well. Stir in a pinch of salt and pepper. After 25 minutes, uncover gratin, sprinkle evenly with breadcrumb mixture, and bake uncovered another 25 minutes. To brown the breadcrumbs as in the pictures, heat about 6 inches from the broiler for 2 to 3 minutes, watching carefully so it doesn’t burn. Cool 5 to 10 minutes before serving.


Nutrition: vegetarian

Adapted from The New Vegetarian Cooking for Everyone by Deborah Madison.

  • Prep Time: 50 mins
  • Cook Time: 55 mins
  • Category: Dinner
  • Cuisine: Vegetarian