01 -
Turn your oven on and set the temperature to 375°F (190°C).
02 -
Coat the bottom and edges of an 8x13-inch pan with a bit of oil or butter.
03 -
Stir together crabmeat, lemon juice, breadcrumbs, melted butter, half the Parmesan, Dijon mustard, horseradish, garlic powder, and onion powder in a large bowl until it's evenly mixed.
04 -
Use a cookie scoop to stuff the mixture into the mushroom caps, pressing it down so it stays in place.
05 -
Sprinkle the rest of the Parmesan cheese across the tops of the stuffed mushrooms.
06 -
Place the mushrooms in the oven and bake them until they're soft and golden, around 15 to 20 minutes.
07 -
Take the baking pan out of the oven and serve the mushrooms while they're still hot.