1. Preheat the oven:
   Preheat your oven to 375°F (190°C). Lightly grease a baking sheet or line it with parchment paper to prevent sticking.

2. Prepare the mushrooms:
   Gently clean the mushroom caps with a damp paper towel to remove any dirt. Carefully remove the stems by twisting them off. Save the stems! Finely chop them and set them aside for the filling.

3. Make the filling:
   In a medium mixing bowl, combine the softened cream cheese, grated Parmesan, breadcrumbs, melted butter, chopped parsley, garlic, salt, pepper, and crushed red pepper flakes (if using). Stir in the chopped mushroom stems, mixing everything until well combined. If the mixture feels too thick, you can add a small splash of olive oil or a tablespoon of milk to loosen it slightly.

4. Stuff the mushroom caps:
   Spoon the filling mixture into each mushroom cap, pressing down lightly to pack the filling inside. Be generous with the stuffing—it’s the best part! If you like, sprinkle a little shredded mozzarella on top of each stuffed mushroom for a cheesy finish.

5. Bake the stuffed mushrooms:
   Arrange the stuffed mushrooms on the prepared baking sheet, making sure they’re evenly spaced. Bake in the preheated oven for 15-20 minutes, or until the mushrooms are tender and the filling is golden and bubbly. If you added mozzarella, it should be melted and slightly browned on top.

6. Optional broil for a golden finish:
   If you prefer a crispier top, turn on the broiler for the last 2-3 minutes of baking, but keep a close eye on them to avoid burning.

7. Rest and serve:
   Remove the stuffed mushrooms from the oven and let them cool for a few minutes before serving. Garnish with extra fresh parsley if desired.

Serving Suggestions:

• Serve as an appetizer or side dish alongside your main course.
• Pair with a light salad or a refreshing vegetable dish to balance the richness.
• You can also serve them as a party snack with cocktails or wine.