Preheat your oven to 400°F (200°C). Lightly grease a 9×13-inch baking dish with cooking spray or a little olive oil so the stuffed chicken breasts can sit in a single, uncrowded layer.
cooking spray or additional olive oil
Heat 1 tablespoon olive oil (or butter) in a medium skillet over medium heat. Add the minced garlic and cook for about 30 seconds, just until fragrant. Add the spinach and cook, stirring, for 2–3 minutes, until wilted and bright green. Transfer the spinach mixture to a cutting board, chop it into smaller pieces, then place in a medium bowl. Add the softened cream cheese, shredded mozzarella, grated Parmesan, 1/4 teaspoon kosher salt, 1/4 teaspoon black pepper, red pepper flakes (if using), and chopped fresh herbs. Stir until the mixture is creamy and well combined.
2 tablespoons olive oil, 4 cups fresh baby spinach, 2 cloves garlic, 4 ounces cream cheese, 1/2 cup shredded mozzarella cheese, 1/4 cup grated Parmesan cheese, 1/4 teaspoon kosher salt, 1/4 teaspoon black pepper, 1/4 teaspoon red pepper flakes, 1 tablespoon fresh parsley or basil
Pat the chicken breasts dry with paper towels. Using a sharp knife, carefully cut a horizontal slit into the thickest side of each breast to create a pocket, leaving three sides intact and being careful not to cut all the way through.
4 large boneless, skinless chicken breasts
In a small bowl, combine 1 teaspoon kosher salt, 1/2 teaspoon black pepper, 1 teaspoon garlic powder, 1 teaspoon onion powder, and 1 teaspoon smoked paprika. Drizzle or brush the chicken with 1 tablespoon olive oil, then sprinkle the seasoning mix evenly over both sides of each breast, pressing gently so it adheres.
4 large boneless, skinless chicken breasts, 2 tablespoons olive oil, 1 teaspoon kosher salt, 1/2 teaspoon black pepper, 1 teaspoon garlic powder, 1 teaspoon onion powder, 1 teaspoon smoked paprika
Divide the spinach-cheese filling into four equal portions. Carefully spoon or press the filling into the pocket of each chicken breast, distributing it as evenly as possible. If needed, secure the opening of each breast with toothpicks to help keep the filling inside.
4 large boneless, skinless chicken breasts, 4 ounces cream cheese, 1/2 cup shredded mozzarella cheese, 1/4 cup grated Parmesan cheese, toothpicks
Place the stuffed chicken breasts in the prepared baking dish in a single layer. Bake at 400°F (200°C) for 22–28 minutes, depending on thickness, until the internal temperature of the thickest part of the chicken (not the filling) reaches 165°F (74°C).
4 large boneless, skinless chicken breasts
If the tops of the chicken look pale once fully cooked, switch the oven to broil and cook for 1–2 minutes, watching closely, until lightly browned and golden on top.
Remove the baking dish from the oven and let the stuffed chicken breasts rest for 5–7 minutes to allow the juices to redistribute. Remove any toothpicks, garnish with additional chopped fresh herbs if desired, and serve warm.
1 tablespoon fresh parsley or basil, toothpicks