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Caramelized Onion-Stuffed Mushrooms
Kathie Clane

Caramelized Onion-Stuffed Mushrooms

Juicy mushrooms stuffed with sweet caramelized onions, breadcrumbs, and cheese, baked to golden perfection—a delightful, crowd-pleasing appetizer.
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Prep Time 20 minutes
Cook Time 30 minutes
Additional Time 10 minutes
Total Time 1 hour
Course: Uncategorized
Cuisine: Italian-inspired
Calories: 226
Ingredients Method Notes

Ingredients
  

  • 16 medium-sized button or cremini mushrooms
  • 2 large yellow onions thinly sliced
  • 2 tbsp olive oil
  • 1 tbsp butter
  • 2 garlic cloves minced
  • 1/2 cup panko breadcrumbs
  • 1/3 cup grated Parmesan cheese
  • 1/4 cup shredded mozzarella cheese
  • 2 tbsp fresh parsley chopped (plus extra for garnish)
  • 1 tsp fresh thyme leaves or 1/2 tsp dried thyme
  • Salt and pepper to taste

Method
 

  1. Prepare the Mushrooms: Preheat the oven to 375°F (190°C). Remove the mushroom stems and scoop out a bit of the center to create room for the filling. Arrange the caps on a baking sheet lined with parchment paper. Bake for 10 minutes, then set aside to cool.
  2. Caramelize the Onions: Heat olive oil and butter in a skillet over medium heat. Add the onions with a pinch of salt, stirring occasionally for 20-25 minutes until golden and caramelized. Add garlic and cook for an additional minute.
  3. Prepare the Filling: In a bowl, mix the caramelized onions, panko breadcrumbs, Parmesan cheese, mozzarella, parsley, thyme, salt, and pepper. Taste and adjust seasoning as needed.
  4. Stuff the Mushrooms: Fill each mushroom cap generously with the prepared mixture, pressing slightly to ensure the filling stays in place.
  5. Bake to Perfection: Return the stuffed mushrooms to the oven and bake for 15-20 minutes, until the tops are golden and bubbly. Garnish with fresh parsley before serving.

Notes

  • Double the recipe for larger gatherings.
  • Pre-caramelize onions and refrigerate to save time on the day of preparation.