These little mushrooms are everything a party appetizer should be: rich, savoury, and just a little bit fancy while being easy to make. Creamy Brie melts into each mushroom cap while a garlicky, caper-flecked Panko topping toasts up golden and crunchy in the oven.
Melt 3 tablespoons of butter in a large non-stick skillet over medium-high heat. Add the mushrooms and toss to coat, then season with salt and pepper. Cook for 2-3 minutes per side, until lightly golden. Transfer the mushrooms to a large baking dish, cup side up.
Reduce the heat to medium-low and add the remaining 1 tablespoon of butter to the skillet. Once melted, add the capers and garlic. Cook for 3-5 minutes, stirring frequently, until the garlic softens and turns fragrant. Do not let the garlic brown, or it will taste bitter.
Add the panko breadcrumbs and season lightly with salt and pepper. Stir until the crumbs are completely coated in butter, then remove the pan from the heat. Stir in the parsley (if using). Allow the breadcrumb filling to cool for a few minutes before handling.
Press a piece of Brie into each mushroom cap, pushing it down gently. Spoon about 1 teaspoon of the breadcrumb filling on top of each mushroom.
Bake for 18-22 minutes, or until the breadcrumbs are golden brown and the Brie has melted and is bubbling at the edges. Let cool for 5 minutes before serving. Serve warm or at room temperature.
Leftover mushrooms will keep in an airtight container in the refrigerator for up to 2 days. For the best texture, reheat in an air fryer or toaster oven at 350°F until warmed through, about 5-7 minutes.
Notes
About the Brie: Double-cream Brie gives the best melt and richest flavor. Any soft, ripe Brie will work. No need to remove the rind before adding it to the mushrooms.Cleaning mushrooms: Wipe with a damp cloth or rinse briefly under cold water and pat dry. Do not soak them, or they will steam instead of browning.Mushroom stems: Save the stems for stocks, soups, or stir-fries.Batch cooking: If your skillet can't hold all the mushrooms at once, brown them in two batches using half the butter each time.Variations:
Deluxe: Fold cooked crab or lobster meat into the breadcrumb filling.
Extra-cheesy: Swap the Brie for Gruyere, Parmesan, feta, or cream cheese.
Thanksgiving: Use fresh sage instead of parsley.
Low-carb: Omit the breadcrumbs and spoon the caper-garlic butter directly into the caps before adding the Brie.