Preheat the Oven: Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
Prepare the Mushrooms: Clean the mushrooms and remove the stems. Finely chop the reserved stems.
Mix the Filling: In a bowl, combine the breadcrumbs, grated Parmesan cheese, chopped lobster meat, minced onion, minced garlic, chopped parsley, and the chopped mushroom stems. Mix well.
Fill the Mushrooms: Place the mushroom caps on the prepared baking sheet. Stuff each mushroom generously with the filling mixture.
Bake: Drizzle the melted butter over the stuffed mushrooms and bake in the preheated oven for 15-20 minutes or until the mushrooms are tender and the tops are golden brown.
Serve: Arrange the stuffed mushrooms on a serving platter and garnish with additional parsley if desired. Serve hot.