Caramelized Onion Gruyere Squash

Featured in: One-Pot Warm Meals

This dish features tender roasted acorn squash halves filled with slowly caramelized onions and melted Gruyere cheese. The onions develop a deep, sweet flavor through low heat cooking with butter, sugar, and balsamic vinegar. The squash is roasted cut side down to intensify sweetness before being filled and baked again to melt the cheese. Finished with fresh thyme and parsley, it offers a warm, savory, and herbaceous centerpiece ideal for vegetarian dining.

Updated on Sun, 23 Nov 2025 09:58:00 GMT
Golden, bubbly Caramelized Onion Gruyere Acorn Squash, a vegetarian main course with savory herbs. Save to Pinterest
Golden, bubbly Caramelized Onion Gruyere Acorn Squash, a vegetarian main course with savory herbs. | frostkettle.com

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

This dish has become a favorite in my household for its rich flavors and simple preparation

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

Preheat oven:
Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper
Prepare squash:
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
Caramelize onions:
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
Add vinegar and thyme:
Stir in the balsamic vinegar and fresh thyme. Cook for 2 minutes, then remove from heat
Turn squash and adjust oven:
Remove squash from the oven and carefully turn cut side up. Reduce oven temperature to 375°F (190°C)
Fill squash:
Evenly distribute the caramelized onions among the squash cavities. Top each half with grated Gruyere cheese
Bake:
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
Garnish and serve:
Remove from the oven. Garnish with fresh parsley and additional thyme leaves before serving
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| frostkettle.com

This recipe always brings my family together, sharing smiles over every bite

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

Nutritional Information

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

Melted Gruyere blankets the savory Caramelized Onion Gruyere Acorn Squash, perfect for a cozy fall feast. Save to Pinterest
Melted Gruyere blankets the savory Caramelized Onion Gruyere Acorn Squash, perfect for a cozy fall feast. | frostkettle.com

Enjoy this cozy dish at your next family dinner for a warm comforting meal

Recipe Questions & Answers

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

Cook sliced onions over medium-low heat with butter and olive oil, stirring occasionally, until golden and soft, adding sugar halfway to enhance sweetness.

Why roast the acorn squash cut side down?

Roasting cut side down concentrates the natural sugars and softens the flesh for a sweeter, more tender texture.

Can I substitute Gruyere cheese?

Yes, similar melting cheeses like Emmental or Comté can be used, but Gruyere provides a distinct nutty flavor and smooth melt.

How do fresh herbs enhance the dish?

Thyme and parsley add bright, aromatic notes that complement the rich sweetness of the onions and creamy cheese.

Is this suitable for gluten-free diets?

Yes, acorn squash and cheese are naturally gluten-free, but always verify the cheese label to ensure no additives contain gluten.

Caramelized Onion Gruyere Squash

Roasted acorn squash halves with caramelized onions and melted Gruyere topped with fresh herbs.

Prep Duration
20 minutes
Time to Cook
60 minutes
Overall Time
80 minutes
Created by Nora Whitman


Skill Level Medium

Cuisine Modern American

Makes 4 Serving Size

Dietary Information Meatless, Wheat-Free

What You 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 grated Gruyere cheese
02 2 tablespoons fresh thyme leaves, plus extra for garnish
03 1/4 cup chopped fresh parsley (optional)

How-To Steps

Step 01

Preheat oven and prepare squash: Preheat oven to 400°F. Line a baking sheet with parchment paper.

Step 02

Season and roast squash: Brush the cut sides of the acorn 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 unsalted 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 sugar halfway through cooking to enhance caramelization.

Step 04

Add flavorings to onions: Stir in balsamic vinegar and fresh thyme into the caramelized onions. Continue cooking for 2 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 squash with onion mixture and cheese: Divide caramelized onions evenly among squash cavities. Top each half with grated Gruyere cheese.

Step 07

Bake filled squash: Return stuffed squash to the 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 fresh 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 Info

Review every ingredient for allergens. Ask a healthcare professional if unsure.
  • Contains dairy from butter and Gruyere cheese

Nutrition Details (Each Serving)

Given for informational purposes, this isn't medical advice.
  • Energy Value: 340
  • Fats: 19 g
  • Carbohydrates: 32 g
  • Proteins: 12 g