Caramelized Onion and Blue Cheese Stuffed Mushrooms

These Caramelized Onions and Blue Cheese Stuffed Mushrooms are a crowd-pleasing appetizer or a delicious side dish that’s full of rich, savory flavor! Delicious stuffed mushrooms filled with caramelized onions, blue cheese, and buttery breadcrumbs—perfect for any occasion!

With buttery, sweet onions, tangy blue cheese, and tender baby bella mushrooms, this dish is pure comfort food in bite-sized form. Perfect for dinner parties, holiday gatherings, or just a cozy night in!

Ingredients You Will Need:

• Whole baby bella mushrooms
• Yellow onion
• Garlic
• Butter
• Seasoned Breadcrumbs
• Blue cheese

Step-by-Step Instructions:

1. Prep the mushrooms. Start by cleaning and drying your baby bella mushrooms. Remove the stems and set them aside. Place the mushrooms top side down in an oven-safe pan. Preheat your oven to 350°F.
2. Caramelize the onions. Peel and roughly chop your onions until you have about 3 cups. In a skillet, melt 1/2 cup butter over low heat. Add the chopped onions and cook slowly, stirring occasionally, until they turn soft, golden, and caramelized. This process take about 30-45 minutes, so be patient- it’s so worth it!
3. Add the garlic. One the onions are beautifully caramelized, stir in the minced garlic and cook for 2 minutes until fragrant. Remove the skillet from heat and let it cool for about 5 minutes.
4. Make the filling. After the onion mixture has cooled slightly, stir in 1/2 cup of breadcrumbs, try our seasoned breadcrumbs recipe! If you see butter pooling at the bottom of the pan, add the extra 1/4 cup of breadcrumbs a little at a time until the butter is mostly absorbed but the mixture is still moist and buttery. Gently stir in 3 ounces of blue cheese.
5. Stuff the mushrooms. Spoon the filling generously into each mushroom, mounding it high. Top each stuffed mushroom with a small chunk of the remaining blue cheese for an extra hit of flavor.
6. Bake the mushrooms at 350°F for 12-15 minutes, until the cheese is melted and the filling is golden brown.
7. Garnish with chopped parsley if desired and serve immediately. These are best enjoyed warm and gooey!

Recipe Notes:

• Not a fan of blue cheese? Try swapping in parmesan, swiss, or even goat cheese!
• Breadcrumb texture, if your filling feels too dry, add a tablespoon or two of melted butter until it’s moist and rich again.
• Make it ahead! You can prepare the filling a day ahead and refrigerate it until you’re ready to stuff and bake the mushrooms.

These Caramelized Onions and Blue Cheese Stuffed Mushrooms are pure magic—earthy, buttery, tangy, and utterly addictive. Whether you’re serving them as an appetizer or a decadent side dish, they’re sure to disappear fast. Enjoy!

More Recipes You Will Love

• Seasoned Breadcrumbs
• Homemade Croutons
• Easy Bacon Stuffed Mushrooms

Emily

Caramelized Onion and Blue Cheese Stuffed Mushrooms

These Caramelized Onions and Blue Cheese Stuffed Mushrooms are the perfect savory bite for parties, holidays, or a cozy appetizer. Tender baby bella mushrooms are filled with a rich mixture of sweet caramelized onions, garlic, buttery breadcrumbs, and bold blue cheese, then baked until golden and bubbly. Easy to make and bursting with flavor, these stuffed mushrooms will quickly become a favorite for any occasion!

Print Recipe Pin Recipe

Prep Time 45 minutes mins

Cook Time 15 minutes mins

Total Time 1 hour hr

Servings: 12

Course: Appetizers

Cuisine: American

Calories: 325

Ingredients Method Notes

Ingredients

  

• 1 pound baby bella whole mushrooms cleaned and dried
• 3 cups chopped yellow onions about 3 large onions
• 6 cloves of garlic chopped
• ½ cup butter
• ½ to ¾ cup dry Italian seasoned breadcrumbs
• 5 oz blue cheese

Method

 

1. 1. Prep the Mushrooms: Start by cleaning and drying your baby bella mushrooms. Remove the stems and set them aside. Place the mushrooms top side down in an oven-safe pan. Preheat your oven to 350°F (175°C).
2. 2. Caramelize the Onions: Peel and roughly chop your onions until you have about 3 cups. In a 12” skillet, melt ½ cup of butter over low heat. Add the chopped onions and cook slowly, stirring occasionally, until they turn soft, golden, and caramelized. This process takes about 30–45 minutes, so be patient—it's worth it!
3. 3. Add the Garlic: Once the onions are beautifully caramelized, stir in the minced garlic and cook for 2 minutes until fragrant. Remove the skillet from heat and let it cool for about 5 minutes.
4. 4. Make the Filling: After the onion mixture has cooled slightly, stir in ½ cup of breadcrumbs. If you see butter pooling at the bottom of the pan, add the extra ¼ cup of breadcrumbs a little at a time until the butter is mostly absorbed but the mixture is still moist and buttery. Next, gently mix in 3 ounces of blue cheese.
5. 5. Stuff the Mushrooms: Spoon the filling generously into each mushroom, mounding it high. Top each stuffed mushroom with a small chunk of the remaining blue cheese for an extra hit of flavor.
6. 6. Bake: Bake the mushrooms at 350°F for 12–15 minutes, until the cheese is melted and the filling is golden brown.
7. 7. Serve: Garnish with chopped parsley if desired and serve immediately. These are best enjoyed warm and gooey!

Notes

• Not a fan of blue cheese? Try swapping in parmesan, swiss, or even goat cheese!
• Breadcrumb texture, if your filling feels too dry, add a tablespoon or two of melted butter until it's moist and rich again.
• Make it ahead! You can prepare the filling a day ahead and refrigerate it until you're ready to stuff and bake the mushrooms.