Preheat the Oven: Preheat your oven to 375°F (190°C).
Prepare the Filling: In a large bowl, combine the softened cream cheese, sour cream, mayonnaise, mozzarella cheese, Parmesan cheese, garlic, onion powder, red pepper flakes (if using), and a pinch of salt and pepper. Mix until smooth.
Add Spinach and Artichokes: Fold in the drained spinach and chopped artichokes until well combined.
Prepare the Bagels: Slice the bagels in half and place them on a baking sheet, cut side up.
Top the Bagels: Spread a generous amount of the spinach-artichoke mixture on each bagel half.
Bake: Bake in the preheated oven for about 15-20 minutes, or until the cheese is melted and bubbly, and the bagels are lightly toasted.
Serve: Let cool slightly before serving. Enjoy warm!