Caramelized Onion Gruyere Squash

Featured in: Vegetarian Favorites

This comforting dish features acorn squash halves roasted until tender and stuffed with deeply caramelized onions and melted Gruyere cheese. The squash is first roasted cut-side down to bring out its natural sweetness. Onions are slowly caramelized with a touch of balsamic vinegar and fresh thyme, then layered inside the squash and topped with grated Gruyere before a final baking that melts the cheese to a golden finish. Garnished with fresh parsley and thyme, it offers a warm, satisfying vegetarian main course perfect for any occasion.

Updated on Sun, 23 Nov 2025 15:36:00 GMT
Caramelized Onion Gruyere Squash, melting Gruyere over tender acorn squash, a vegetarian delight. Save
Caramelized Onion Gruyere Squash, melting Gruyere over tender acorn squash, a vegetarian delight. | whisknjoy.com

Acorn squash halves roasted until tender, stuffed with deeply caramelized onions and melty Gruyere cheese, and finished with fresh herbs—a comforting, gourmet vegetarian main perfect for any occasion.

This dish combines tender roasted squash with richly caramelized onions and melty Gruyere cheese for a flavorful experience I enjoy making for family dinners.

Ingredients

  • 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

Step 1:
Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
Step 2:
Brush the cut sides of the acorn squash with olive oil. Season with kosher salt and black pepper. Place squash halves cut side down on the prepared baking sheet and roast for 35–40 minutes or until the flesh is fork-tender.
Step 3:
Meanwhile, heat unsalted butter and olive oil in a large skillet over medium-low heat. Add the sliced onions and kosher salt. Cook, stirring occasionally, for 30–35 minutes until the onions are deeply golden and soft. Sprinkle with sugar about halfway through to encourage caramelization.
Step 4:
Stir in the balsamic vinegar and fresh thyme. Cook for 2 minutes then remove from heat.
Step 5:
Remove squash from the oven and carefully turn cut side up. Reduce oven temperature to 375°F (190°C).
Step 6:
Evenly distribute the caramelized onions among the squash cavities. Top each half with grated Gruyere cheese.
Step 7:
Return the filled squash to the oven and bake for 15–20 minutes or until the cheese is melted and golden brown at the edges.
Step 8:
Remove from the oven. Garnish with fresh parsley and additional thyme leaves before serving.
Golden-topped Caramelized Onion Gruyere Squash overflowing with savory onions, a delicious main course. Save
Golden-topped Caramelized Onion Gruyere Squash overflowing with savory onions, a delicious main course. | whisknjoy.com

This recipe often brings my family together as we share the warm flavors and cozy moments around the dinner table.

Notes

Roast squash cut side down to concentrate sweetness and enhance caramelization. Caramelize onions slowly over low heat to avoid burning and bitterness. Grate cheese yourself for the best melting texture. Easily doubled for meal prep or gatherings. Pairs beautifully with a green salad or crispy sourdough toast. Use certified gluten-free cheese if needed.

Required Tools

Chefs knife, Cutting board, Baking sheet, Parchment paper, Large skillet, Wooden spoon, Grater

Allergen Information

Contains dairy (butter, Gruyere cheese). Naturally gluten-free always check cheese labels to confirm. Vegetarian-friendly. No nuts or soy in the base recipe but verify all ingredient labels for cross-contamination if needed.

The savory aroma of Caramelized Onion Gruyere Squash emanates from a baked acorn squash, ready to serve. Save
The savory aroma of Caramelized Onion Gruyere Squash emanates from a baked acorn squash, ready to serve. | whisknjoy.com

This recipe is a perfect centerpiece for a hearty vegetarian meal that impresses without fuss.

Recipe FAQ

Why roast the squash cut side down?

Roasting squash cut side down concentrates sweetness and helps caramelize the flesh for a richer flavor and tender texture.

How can I caramelize onions without burning them?

Cook onions slowly over low to medium-low heat, stirring occasionally, and add a bit of sugar halfway to encourage caramelization without bitterness.

What type of cheese works best for melting in this dish?

Gruyere cheese melts smoothly and browns nicely, adding a nutty, creamy element that complements the sweet onions and squash.

Can this dish be prepared in advance?

Yes, you can roast the squash and caramelize onions ahead of time, then assemble and bake just before serving to save time.

What herbs enhance the flavors here?

Fresh thyme is cooked with the onions for depth, and parsley is added as garnish to provide a fresh, bright contrast.

Is this dish suitable for gluten-free diets?

Yes, the ingredients are naturally gluten-free, but verify that the cheese is certified gluten-free to avoid cross-contamination.

Caramelized Onion Gruyere Squash

Acorn squash halves roasted and filled with caramelized onions and Gruyere, topped with fresh herbs.

Prep duration
20 min
Cook duration
60 min
Complete duration
80 min
Created by Sophia Turner

Classification Vegetarian Favorites

Skill Level Medium

Cultural Background Modern American

Output 4 Portion Count

Dietary considerations Meat-Free, No Gluten

Components

Squash

01 2 medium acorn squash, halved lengthwise and seeded
02 2 tablespoons olive oil
03 1/2 teaspoon kosher salt
04 1/4 teaspoon ground black pepper

Caramelized Onions

01 2 large yellow onions, thinly sliced
02 2 tablespoons unsalted butter
03 1 tablespoon olive oil
04 1/2 teaspoon kosher salt
05 1/2 teaspoon granulated sugar
06 2 teaspoons balsamic vinegar
07 2 tablespoons fresh thyme leaves

Filling and Garnish

01 1 1/2 cups Gruyere cheese, grated
02 1/4 cup chopped fresh parsley (optional)

Preparation Steps

Stage 01

Prepare Oven and Squash: Preheat oven to 400°F. Line a baking sheet with parchment paper. Brush cut sides of squash with olive oil; season with kosher salt and black pepper. Place cut side down on the baking sheet and roast for 35 to 40 minutes until fork-tender.

Stage 02

Caramelize Onions: In a large skillet over medium-low heat, melt butter with olive oil. Add sliced onions and salt, cooking gently while stirring occasionally for 30 to 35 minutes until deeply golden and soft. Sprinkle sugar halfway through cooking to enhance caramelization.

Stage 03

Finish Onions: Stir in balsamic vinegar and fresh thyme leaves. Cook for an additional 2 minutes, then remove from heat.

Stage 04

Assemble Squash: Remove squash from oven and turn cut side up. Reduce oven temperature to 375°F. Evenly fill squash cavities with caramelized onions, then top with grated Gruyere cheese.

Stage 05

Bake Filled Squash: Return squash halves to oven and bake for 15 to 20 minutes until cheese is melted and edges turn golden brown.

Stage 06

Garnish and Serve: Remove from oven and garnish with chopped fresh parsley and additional thyme leaves as desired before serving.

Necessary tools

  • Chef's knife
  • Cutting board
  • Baking sheet
  • Parchment paper
  • Large skillet
  • Wooden spoon
  • Grater

Allergy details

Review all ingredients for potential allergens and consult with healthcare professionals if you're unsure about any item.
  • Contains dairy from butter and Gruyere cheese.
  • Check cheese labels to confirm gluten-free status.

Nutritional content (each portion)

These values are provided as estimates only and shouldn't replace professional medical guidance.
  • Energy: 340
  • Fats: 19 g
  • Carbohydrates: 32 g
  • Proteins: 12 g