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Caramelized Onion and Gruyère Stuffed Acorn Squash Recipe

4.9 from 98 reviews

This Caramelized Onion Gruyere Squash recipe features tender roasted acorn squash halves filled with sweet, golden caramelized onions and topped with melted Gruyere cheese. Enhanced with fresh thyme and a touch of balsamic vinegar, it’s a perfect savory and comforting dish ideal for fall or holiday meals.

Ingredients

Scale

Squash

  • 2 medium acorn squash, halved lengthwise and seeded
  • 2 tablespoons olive oil
  • 1/2 teaspoon kosher salt
  • 1/4 teaspoon ground black pepper

Caramelized Onions

  • 2 large yellow onions, thinly sliced
  • 2 tablespoons unsalted butter
  • 1 tablespoon olive oil
  • 1/2 teaspoon kosher salt
  • 1/2 teaspoon granulated sugar
  • 2 teaspoons balsamic vinegar

Filling and Garnish

  • 1 1/2 cups Gruyere cheese, grated
  • 2 tablespoons fresh thyme leaves, plus more for garnish
  • 1/4 cup chopped fresh parsley (optional)

Instructions

  1. Prepare Oven and Pan: Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper to prevent sticking and ease cleanup.
  2. Season and Roast Squash: Brush the cut sides of the acorn squash halves with olive oil. Season evenly with kosher salt and black pepper. Place the squash halves cut side down on the lined baking sheet and roast for 35 to 40 minutes until the flesh is tender when pierced with a fork.
  3. Caramelize Onions: While the squash roasts, heat unsalted butter and olive oil in a large skillet over medium-low heat. Add the thinly sliced onions and kosher salt. Cook the onions slowly, stirring occasionally, for about 30 to 35 minutes until they become soft and richly golden. Halfway through, sprinkle the sugar over the onions to encourage caramelization.
  4. Finish Onions with Vinegar and Thyme: Add balsamic vinegar and fresh thyme leaves to the skillet with the caramelized onions. Stir well and cook for an additional 2 minutes to meld the flavors, then remove the skillet from heat.
  5. Fill and Bake Squash: Carefully remove the roasted squash from the oven and flip them so the cut side is up. Reduce the oven temperature to 375°F (190°C). Evenly spoon the caramelized onions into each squash cavity and top generously with the grated Gruyere cheese.
  6. Bake Filled Squash: Return the filled squash halves to the oven and bake for 15 to 20 minutes, or until the Gruyere cheese is fully melted, golden brown, and bubbly around the edges.
  7. Garnish and Serve: Remove the squash from the oven. Garnish with additional fresh thyme leaves and chopped parsley if desired. Serve warm as a delicious side or vegetarian main dish.

Notes

  • Ensure to cook the onions slowly to achieve the best caramelization without burning.
  • Using fresh thyme adds a lovely aromatic flavor, but dried thyme can be substituted if needed.
  • Gruyere cheese melts beautifully, but you can substitute with Fontina or a mild Swiss cheese if unavailable.
  • To speed up caramelizing onions, you can increase the heat slightly, but be vigilant to avoid burning.
  • This dish is naturally vegetarian and can be part of a gluten-free meal when serving.

Keywords: caramelized onion squash, acorn squash recipe, roasted squash with cheese, vegetarian autumn side dish, Gruyere squash bake