Prep the Chicken. Start by making cuts across each chicken breast, about 3/4 down, ensuring not to cut all the way through. Season the chicken with salt and pepper.
Prepare the Filling. In a bowl, mix the jalapeno slices, spinach, ricotta, mozzarella, and minced garlic. Add any additional herbs or seasonings as desired.
Stuff the Chicken. Carefully stuff each slit with the spinach and cheese mixture. Sprinkle with additional salt, pepper, and any other desired seasonings.
Bake to Perfection. Bake in a preheated oven at 375°F for 20-25 minutes, or until the chicken is thoroughly cooked and the cheese is melted and bubbly.
Garnish and Serve. Let the chicken rest for a few minutes after baking. Garnish with fresh herbs or a drizzle of pesto sauce before serving.