Preheat Oven: Set your oven to 375°F (190°C) and line a baking sheet with parchment paper.
Prep Mushrooms: Clean mushrooms with a damp cloth and gently remove stems. Place mushroom caps upside down on the prepared baking sheet.
Make Filling: In a mixing bowl, combine crab meat, cream cheese, breadcrumbs, Parmesan, mayo, garlic, parsley, onion powder, salt, and pepper. Mix until smooth.
Stuff the Mushrooms: Use a spoon to fill each mushroom cap generously with the crab mixture.
Top and Bake: Sprinkle a bit of extra breadcrumbs on top for crunch. Drizzle lightly with olive oil.
Bake: Bake for 18–20 minutes or until golden and bubbly.
Serve: Let cool slightly, garnish with fresh parsley if desired, and serve warm.