Use a sharp knife to carefully slice horizontally into each chicken breast to create a pocket, being careful not to cut all the way through. This creates a space for the filling while keeping the chicken intact.
Season the inside of each pocket with a pinch of salt and pepper, then set aside.
In a small bowl, mix together the shredded mozzarella, chopped basil or thyme, roasted peppers, and minced garlic to make the filling. Adjust salt and pepper to taste.
Spoon about 1-2 tablespoons of the filling into each chicken pocket, pressing gently to pack it in. Use toothpicks to seal the opening if needed.
Heat the olive oil in a skillet over medium-high heat. Sear each stuffed chicken breast for 2-3 minutes per side until they develop a deep golden brown crust and smell nutty.
Transfer the seared chicken breasts to a baking dish or sheet and bake in a preheated oven at 180°C (350°F) for 20-25 minutes, or until the internal temperature reaches 75°C (165°F) and the chicken is cooked through.
Remove the chicken from the oven and let it rest for 5 minutes. This helps juices redistribute and keeps the filling from spilling out when sliced.
Slice into the chicken to reveal the gooey, colorful filling inside. Serve immediately, garnished with extra herbs if desired.
