Make stuffing.
Like an omelette, use whatever sound good to make stuffing.
One suggestion:
1 – Chopped Mushrooms
2 – Chopped Onion
3 – Oregano
Grated Cheese
Combine ingredients 1, 2 and 3, then saute in a little olive oil until onion is transparent. Let cool. Then add cheese.
Make a cavity in the chicken breast using a sharp knife. Make about a one inch incision, push knife through to create a cavity. Use knife to get cavity as big as possible without cutting alt the way through sides.
Push as much stuffing as you can fit into the cavity.
Sprinkle some grated cheese on the breast.
Bake in preheated 425°F oven 30 minutes or until chicken is to an internal temperature of 165°F.