Caramelized Onion & Gruyère Stuffed Mushrooms Recipe

Introduction

These caramelized onion and Gruyère stuffed mushrooms are a savory and elegant appetizer that combines sweet, tender onions with rich, melted cheese. Perfect for entertaining or a cozy snack, they bring out the best in simple ingredients.

Ingredients

• 12 large white or cremini mushrooms, stems removed and reserved
• 1 medium onion, thinly sliced
• 2 tablespoons butter
• 1/2 teaspoon sugar
• 1/4 teaspoon salt
• 1/4 teaspoon black pepper
• 1/2 cup grated Gruyère cheese
• 1/4 cup fresh breadcrumbs (preferably panko)
• 1 tablespoon olive oil
• 1 tablespoon fresh thyme, chopped (optional)
• 1/4 cup grated Parmesan cheese

Instructions

1. Step 1: Preheat the oven to 375°F (190°C). Line a baking sheet with parchment paper or lightly grease it.
2. Step 2: In a skillet, melt butter over medium heat. Add the sliced onions, salt, pepper, and sugar. Cook, stirring occasionally, until the onions are soft and golden brown, about 15–20 minutes. Set aside to cool slightly.
3. Step 3: While the onions caramelize, brush the mushroom caps with olive oil and place them on the prepared baking sheet, cavity side up.
4. Step 4: Finely chop the reserved mushroom stems and mix them with the caramelized onions, Gruyère cheese, breadcrumbs, and Parmesan in a bowl. Adjust seasoning to taste with salt and pepper.
5. Step 5: Spoon the onion and cheese mixture into each mushroom cap, pressing it in gently to pack it well.
6. Step 6: Bake the stuffed mushrooms in the preheated oven for 15–20 minutes, until the mushrooms are tender and the cheese is melted and golden brown.
7. Step 7: Garnish with fresh thyme if desired and serve immediately.

Tips & Variations

• For extra richness, add a small amount of cream cheese or mascarpone to the filling.
• These mushrooms can be made ahead; refrigerate them unbaked and bake when ready to serve.
• Try swapping Gruyère for another melting cheese like Swiss or fontina for a different flavor profile.

Storage

Store any leftover stuffed mushrooms in an airtight container in the refrigerator for up to 2 days. Reheat in a preheated oven at 350°F (175°C) for 10 minutes until warmed through and cheese is bubbly. Avoid microwaving to keep the texture intact.

How to Serve

Serve this delicious recipe with your favorite sides.

FAQs

Can I use other types of mushrooms for this recipe?

Yes, cremini or white button mushrooms work best for stuffing due to their size and shape, but portobello caps can also be used for a larger portion.

Can I prepare the filling ahead of time?

Absolutely. You can make the caramelized onion and cheese mixture in advance and store it in the refrigerator. Assemble and bake the mushrooms just before serving for the best texture and flavor.

Caramelized Onion & Gruyère Stuffed Mushrooms Recipe

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★★★★★

4.7 from 118 reviews

These Caramelized Onion & Gruyère Stuffed Mushrooms are a delicious appetizer featuring tender mushrooms filled with a savory blend of sweet caramelized onions, creamy Gruyère cheese, and crunchy breadcrumbs, all baked until golden and bubbly. Perfect for parties or a flavorful snack.

• Author: Lisa
• Prep Time: 20 minutes
• Cook Time: 20 minutes
• Total Time: 40 minutes
• Yield: 12 stuffed mushrooms 1x
• Category: Appetizer
• Method: Baking
• Cuisine: French-inspired
• Diet: Vegetarian

Ingredients

Scale 1x2x3x

Mushroom Preparation

• 12 large white or cremini mushrooms, stems removed and reserved
• 1 tablespoon olive oil

Caramelized Onion Filling

• 1 medium onion, thinly sliced
• 2 tablespoons butter
• 1/2 teaspoon sugar
• 1/4 teaspoon salt
• 1/4 teaspoon black pepper

Cheese and Breadcrumb Mixture

• 1/2 cup grated Gruyère cheese
• 1/4 cup fresh breadcrumbs (preferably panko)
• 1/4 cup grated Parmesan cheese
• 1 tablespoon fresh thyme, chopped (optional)

Instructions

1. Preheat Oven: Preheat the oven to 375°F (190°C). Line a baking sheet with parchment paper or lightly grease it to prevent sticking.
2. Caramelize Onions: In a skillet, melt the butter over medium heat. Add the thinly sliced onions along with salt, pepper, and sugar. Cook, stirring occasionally, until the onions become soft, golden brown, and caramelized, about 15–20 minutes. Remove from heat and let cool slightly.
3. Prepare Mushrooms: Brush the mushroom caps with olive oil and arrange them cavity side up on the prepared baking sheet.
4. Make Filling: Finely chop the reserved mushroom stems and combine them in a bowl with the caramelized onions, grated Gruyère cheese, fresh breadcrumbs, and grated Parmesan cheese. Season the mixture with additional salt and pepper to taste, and mix well.
5. Stuff Mushrooms: Spoon the onion and cheese filling into each mushroom cap, pressing gently to pack the mixture securely inside.
6. Bake: Place the stuffed mushrooms in the preheated oven and bake for 15–20 minutes until the mushrooms are tender and the cheese on top is melted and golden brown.
7. Garnish & Serve: Sprinkle with fresh thyme if desired and serve immediately for best flavor and texture.

Notes

• For extra richness, add a small amount of cream cheese or mascarpone to the filling.
• These mushrooms can be made ahead of time; refrigerate them unbaked and bake just before serving.
• Swap Gruyère cheese with other melting cheeses like Swiss or fontina for a different flavor profile.

Keywords: stuffed mushrooms, caramelized onion, Gruyère cheese, appetizer, baked mushrooms, party snacks, vegetarian appetizer