Prep Oven & Baking Sheet: Preheat your oven to 400°F (200°C). Line a large rimmed baking sheet with parchment paper or place a wire rack inside the sheet pan (baking on a wire rack elevates the mushrooms, allowing steam to escape for extra crispy caps!).

Clean & Prep Mushrooms: Wipe the cremini mushrooms clean with a damp paper towel (never soak mushrooms in water, or they will absorb moisture and become soggy). Gently snap off the stems and set them aside. Finely mince 1/2 cup of the mushroom stems for the filling. Arrange the hollowed mushroom caps on the prepared baking sheet, cavity facing up, and lightly brush the outside of each cap with olive oil and a pinch of salt.

Sauté Aromatics: Melt 1 tablespoon butter in a small skillet over medium heat. Add the minced mushroom stems and minced garlic. Sauté for 3 to 4 minutes until the mushroom pieces are tender and all released liquid has evaporated. Remove from heat and allow to cool for 5 minutes.

Mix the Creamy Filling: In a medium bowl, combine the softened cream cheese, 1/2 cup grated Parmesan, the sautéed garlic and mushroom stem mixture, chopped parsley, fresh thyme, sliced scallions, onion powder, black pepper, and cayenne. Stir vigorously with a spatula until completely smooth and evenly blended.

Stuff the Mushrooms: Using a small spoon or cookie scoop, mound a generous tablespoon of the creamy filling into each mushroom cap, pressing lightly to fill the cavity and doming the top slightly.

Make Panko Crust & Top: In a small bowl, stir together the panko breadcrumbs, 2 tablespoons grated Parmesan, and 1.5 tablespoons melted butter until the crumbs are evenly moistened. Generously spoon or press the buttered panko mixture over the top of each stuffed mushroom.

Bake to Golden Perfection: Bake at 400°F (200°C) for 18 to 20 minutes, until the mushroom caps are tender and juicy, the cheese filling is hot and bubbly, and the panko topping is deeply golden brown. Let rest for 5 minutes, garnish with fresh parsley, and serve warm on your party platter!