Heat 1 tablespoon olive oil in a large skillet over medium heat. Add chicken breasts and cook 5 to 7 minutes per side until browned and cooked through.
Remove chicken from heat and slice or shred as desired.
Add the remaining 1 tablespoon olive oil to the skillet. Sauté minced garlic for 1 minute until fragrant.
Add fresh spinach and cook for 2 minutes until wilted.
Reduce heat to low. Stir in cream cheese, Italian seasoning, salt, and pepper. Mix until smooth and creamy.
Mix in ½ cup shredded mozzarella and Parmesan cheese (if using). Stir until combined.
Add cooked chicken to the skillet and stir to coat with sauce.
Transfer mixture into a greased 9x9-inch baking dish. Top with remaining mozzarella cheese.
Bake for 20 minutes until cheese is bubbly and golden on top. Let rest 5 minutes before serving.
Notes
To make gluten-free, ensure all ingredients are certified gluten free. Leftovers store well in the fridge for 3-4 days or in the freezer for up to 3 months.