Preheat oven to 450 degrees F degrees. Line a baking sheet with aluminum foil or lightly grease with oil.
In a Medium mixing bowl, combine the cream cheese, mozzarella, cheddar, Parmesan, and feta cheeses. Toss in chopped spinach, salt, pepper and garlic powder. Mix everything with a fork until the mixture is fully combined.
Arrange sweet peppers on prepared baking sheet. Spoon about 1 tablespoon cheese mixture into each pepper.
Bake in the preheated oven until cheese is melted and bubbling, about 10-15 minutes. Serve warm. Enjoy!