Preheat the Oven:

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

Prepare the Mushrooms:

Clean the mushrooms with a damp paper towel and remove the stems. Set the mushroom caps aside and finely chop the stems.

Make the Filling:

In a large mixing bowl, combine the cream cheese, crab meat, Parmesan cheese, green onions, garlic, breadcrumbs, chopped mushroom stems, parsley, Old Bay seasoning, salt, and pepper. Mix until well combined.

Stuff the Mushrooms:

Spoon the crab mixture into each mushroom cap, mounding it slightly.

Bake the Mushrooms:

Place the stuffed mushrooms on the prepared baking sheet. Drizzle the melted butter over the tops of the mushrooms.

Bake in the preheated oven for 20-25 minutes, or until the mushrooms are tender and the tops are golden brown.