Preheat the Oven : Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper or lightly grease it.
Prepare the Mushrooms ; Gently clean the mushroom caps with a damp paper towel. Remove the stems and hollow out slightly if needed. Brush the caps lightly with olive oil and set them aside, cap side down.
Make the Crab Filling : In a mixing bowl, combine cream cheese, mayonnaise, Parmesan, breadcrumbs, garlic, green onions, lemon juice, Worcestershire sauce, and Old Bay seasoning. Stir until smooth and creamy. Gently fold in the crab meat so it stays in chunks. Taste and adjust with salt and pepper as needed.
Stuff the Mushrooms : Spoon the crab mixture into each mushroom cap, slightly mounding the filling. Sprinkle a little extra Parmesan cheese on top of each stuffed mushroom.
Bake the Mushrooms : Place the mushrooms on the prepared baking sheet. Bake for 18–20 minutes, or until the tops are golden and the filling is bubbly.
Garnish and Serve : Let cool slightly, then garnish with fresh parsley before serving. Serve warm for the best flavor and texture.