Preheat oven to 400.
Slice chicken 5 times, make sure not to cut through completely. (See pictures)
Add minced garlic and cayenne pepper, salt, black pepper, smoked paprika, and onion powder on the chicken. (I mixed the spices in a bowl first and then rolled the chicken breast around in the bowl. I think this better coats the chicken.)
Next, stuff each breast with the peppers and onions.
Add the cheese slices and bake until cooked thoroughly - about 25 minutes or until the internal temperature is 165°.
Remove from oven and serve.