**Preheat oven**:
Preheat your oven to 375°F (190°C). Lightly grease a large baking dish.
**Season the chicken**:
Arrange the chicken breasts in the baking dish and season both sides with salt and pepper.
**Prepare the topping**:
In a mixing bowl, combine the chopped spinach, artichokes, Greek yogurt, Parmesan cheese, 1/2 cup mozzarella, garlic, onion powder, and red pepper flakes (if using). Mix until well combined.
**Assemble the dish**:
Spread the spinach and artichoke mixture evenly over the chicken breasts. Top with the remaining mozzarella cheese.
**Bake**:
Cover the dish with foil and bake for 25 minutes. Remove the foil and bake for an additional 10–15 minutes, or until the chicken is cooked through (internal temperature of 165°F or 74°C) and the cheese is bubbly and golden.
**Serve**:
Let the dish rest for a few minutes before serving. Pair with a side of quinoa, rice, or a simple green salad.