In a large saucepan, light saute the garlic, rosemary, and peppercorns. Put aside in container... In the same pan cook the onions and sugar in the butter until the onions are browned. Remove from heat. Charbroil the chicken and zucchini, basting with the olive oil mixture until the chicken is completely cooked (don't overcook the zucchini-). Place chicken breasts along with the butter mixture, zucchini, and remaining oil mixture in a casserole dish. Place the cheese on top of the chicken and bake for 2-4 minutes, until cheese is well melted.