Preheat oven to 375°F and line a baking sheet with parchment paper.
Clean mushrooms, remove stems, brush with olive oil, and season with salt and pepper.
In a large bowl, mix cream cheese, sour cream, and garlic until smooth.
Add spinach, artichokes, mozzarella (¾ cup), Parmesan, salt, pepper, and red pepper flakes. Stir well.
Spoon filling into mushroom caps and arrange on baking sheet.
In a small bowl, combine breadcrumbs, melted butter, and Parmesan. Sprinkle on top.
Add remaining mozzarella on top of each mushroom.
Bake for 20–25 minutes until golden and bubbly. Broil 2 minutes for crispier tops.
Cool for 5 minutes, garnish with parsley, and serve warm.