01 - Preheat the oven to 375°F. Line a baking sheet with parchment paper.
02 - Clean the mushrooms, remove the stems, and gently hollow out the centers if needed to make more room for filling. Set mushroom caps aside.
03 - Heat olive oil in a skillet over medium heat. Add garlic and sauté for 30 seconds until fragrant.
04 - Add chopped spinach and cook until just wilted, about 2 minutes. Stir in chopped artichoke hearts and cook for 1 minute more. Remove from heat and let cool slightly.
05 - In a mixing bowl, combine cream cheese, sour cream, Parmesan, mozzarella, salt, pepper, and red pepper flakes. Mix until creamy.
06 - Fold in the spinach and artichoke mixture until well combined.
07 - Spoon the filling evenly into each mushroom cap. Place stuffed mushrooms on the prepared baking sheet.
08 - Sprinkle the tops with remaining mozzarella and Parmesan cheese.
09 - Bake for 20 to 25 minutes, until the mushrooms are tender and the tops are golden and bubbly.
10 - Remove from oven and sprinkle with fresh parsley before serving.