Prep the oven and pan. Preheat the oven to 400°F (200°C). Lightly grease a 9x13-inch baking dish or a large oven-safe skillet.
Season the chicken. Place the chicken breasts in the dish.
Drizzle with olive oil and sprinkle with 1/2 teaspoon salt, black pepper, garlic powder, onion powder, and smoked paprika if using. Rub to coat evenly.
Make the cheesy spinach artichoke mixture. In a medium bowl, mix cream cheese, Greek yogurt (or sour cream), and mayonnaise until smooth. Stir in mozzarella, Parmesan, minced garlic, remaining 1/2 teaspoon salt, lemon juice, and red pepper flakes.
Prep the greens. Squeeze as much moisture as possible from the thawed spinach using a clean kitchen towel or paper towels.
Chop the artichokes into small pieces. Fold both into the cheese mixture until evenly combined.
Top the chicken. Spoon the spinach artichoke mixture over each chicken breast, spreading it to fully cover the top. This keeps the meat juicy while it bakes.
Bake. Bake uncovered for 22–28 minutes, or until the chicken reaches an internal temperature of 165°F (74°C) in the thickest part.
The topping should be hot and beginning to brown around the edges.
Broil for color (optional). Switch the oven to broil on high for 1–2 minutes to lightly caramelize the top. Watch closely to avoid burning.
Rest and garnish. Let the chicken rest for 5 minutes. Sprinkle with fresh parsley or chives and serve.