Cutting each chicken breast lengthwise to create the pockets for stuffing, but be very careful not to cut all the way through.
Grate lemon zest on the insides of the pockets using a zester. Add Salt and pepper.
Place one slice of swiss cheese in each seasoned pocket, then add 3 spears of asparagus to the cheese and a few pieces of sun-dried tomatoes. Use toothpicks to hold them all together with the stuffing in place.
With the pockets shut with the toothpicks, place the chicken in a hot pan, and sear the breasts until golden brown, about 3 to 5 minutes per side.
Bake the chicken for 20 to 25 minutes, or until it reaches 165 degrees internally.