01 - Preheat oven to 400°F. Lightly grease a 9x13-inch baking dish with cooking spray or a small amount of oil.
02 - Pat chicken breasts thoroughly dry with paper towels. Drizzle both sides with olive oil, then season evenly with salt and black pepper. Arrange seasoned chicken in the prepared baking dish in a single layer.
03 - In a medium bowl, combine thawed spinach (squeezed dry to remove excess moisture), chopped artichoke hearts, softened cream cheese, sour cream, grated Parmesan, minced garlic, and red pepper flakes. Mix until completely smooth and well blended.
04 - Spread the spinach-artichoke mixture evenly over the top of each chicken breast, using a spoon or spatula to create a uniform layer.
05 - Spoon basil pesto over the creamy topping on each chicken breast. Gently spread to create a thin, even layer without pushing the filling off the chicken.
06 - Distribute shredded mozzarella cheese evenly over the tops of the pesto-covered chicken breasts.
07 - Bake uncovered for 30-35 minutes until chicken is fully cooked (internal temperature reaches 165°F when measured with a meat thermometer) and cheese is melted, golden, and bubbling.
08 - Remove from oven and let the chicken rest for 5 minutes before serving to allow juices to redistribute. Garnish with fresh basil leaves if desired.