Caramelized Onion Gruyere Squash

Featured in: Quick Comfort Plates

This comforting dish features acorn squash halves roasted until tender, then generously filled with slowly caramelized onions that bring a rich sweetness. Topped with grated Gruyere cheese, it’s baked until golden and melty. Fresh thyme and parsley add a bright herbal note that balances the savory and sweet layers. Perfect for a satisfying vegetarian main that marries creamy textures with deep, roasted flavors.

Updated on Sun, 23 Nov 2025 11:05:00 GMT
Golden caramelized onion and Gruyere-stuffed acorn squash, a vegetarian autumn main course. Pin It
Golden caramelized onion and Gruyere-stuffed acorn squash, a vegetarian autumn main course. | platefullyjoy.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 recipe quickly became a family favorite as it combines sweet caramelized onions with savory cheese in a seasonal squash base.

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.
Pin It
| platefullyjoy.com

This dish is a hit at family dinners especially during fall when squash is in season and warm comfort food is desired.

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.

Nutritional Information

Calories 340, Total Fat 19 g, Carbohydrates 32 g, Protein 12 g per serving

Melting Gruyere and savory caramelized onions fill tender Caramelized Onion Gruyere Squash halves, ready to serve. Pin It
Melting Gruyere and savory caramelized onions fill tender Caramelized Onion Gruyere Squash halves, ready to serve. | platefullyjoy.com

This recipe brings together sweet and savory elements with a creamy finish making it a perfect cozy meal.

Recipe FAQs

What is the best way to caramelize onions for this dish?

Cook sliced onions slowly over medium-low heat with butter and olive oil, stirring occasionally to develop a deep golden color without burning.

How do I know when the acorn squash is fully roasted?

Roast squash cut side down until the flesh is tender and easily pierced with a fork, usually about 35-40 minutes at 400°F.

Can I substitute Gruyere cheese with another type?

Gruyere provides a creamy, melty texture with a nutty flavor; good alternatives include Emmental or mozzarella for a milder taste.

Why is balsamic vinegar added to the caramelized onions?

Balsamic vinegar adds a subtle tang and depth that enhances the sweetness of the onions while balancing richness.

How should I serve this dish for best flavor pairing?

Serve warm with a crisp green salad or crusty sourdough to complement the rich and savory elements.

Caramelized Onion Gruyere Squash

Acorn squash roasted to tender perfection, filled with caramelized onions and gooey Gruyere cheese.

Time to Prep
20 minutes
Time to Cook
60 minutes
Overall Time
80 minutes
Recipe by Olivia Reed


Skill Level Medium

Cuisine Modern American

Makes 4 Number of Servings

Diet Info Vegetarian-Friendly, No Gluten

What You'll Need

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

Filling and Garnish

01 1 1/2 cups Gruyere cheese, grated
02 2 tablespoons fresh thyme leaves
03 1/4 cup chopped fresh parsley (optional)

Step-by-Step Guide

Step 01

Preheat Oven and Prepare Baking Sheet: Preheat oven to 400°F. Line a baking sheet with parchment paper.

Step 02

Roast Acorn Squash: Brush cut sides of the squash halves with olive oil; season with kosher salt and black pepper. Place cut side down on the prepared baking sheet and roast for 35 to 40 minutes, until tender when pierced with a fork.

Step 03

Caramelize Onions: Heat butter and olive oil in a large skillet over medium-low heat. Add sliced onions and kosher salt. Cook stirring occasionally for 30 to 35 minutes until deeply golden and soft, sprinkling granulated sugar halfway through cooking to enhance caramelization.

Step 04

Finish Onion Mixture: Stir balsamic vinegar and fresh thyme into the caramelized onions. Cook for 2 more minutes, then remove from heat.

Step 05

Prepare Squash for Filling: Remove squash from oven and carefully turn cut side up. Reduce oven temperature to 375°F.

Step 06

Fill and Top Squash: Divide caramelized onions evenly among squash cavities. Top each half with grated Gruyere cheese.

Step 07

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

Step 08

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

Tools You'll Need

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

Allergy Notice

Be sure to review ingredients for allergens. When unsure, talk with a healthcare provider.
  • Contains dairy (butter, Gruyere cheese).

Nutrition (For Each Serving)

Nutritional details are meant for general guidance. Don't rely on them for medical reasons.
  • Calorie Count: 340
  • Fats: 19 g
  • Carbohydrates: 32 g
  • Proteins: 12 g