Preheat your oven to 375°F (190°C) and prepare a cast iron skillet by spraying it lightly with nonstick spray.

Gently clean the mushrooms with a damp paper towel and remove the stems to hollow out each mushroom.

In a mixing bowl, combine the breadcrumbs, melted butter, salt, and black pepper to create the stuffing mixture.

In a skillet, melt 3 tablespoons of butter, add minced garlic, then whisk in flour, half and half, and Parmesan cheese to make the Alfredo sauce.

Layer half of the Alfredo sauce at the bottom of the skillet, place the mushroom caps on top, and spoon the remaining sauce over each.

Sprinkle grated white cheddar cheese and breadcrumb mixture over the stuffed mushrooms.

Bake for approximately 10 minutes until the mushrooms are tender and cheese is melted, then broil for an additional 2-3 minutes for a golden crust.

Garnish with chopped parsley before serving.