Tangy Rosemary Chicken

Preheat oven to 375 degrees F (190 degrees C).

Place chicken breasts in a 9x13 inch baking dish. Put several slices of onion on top.

In a medium saucepan over medium heat stir in ketchup vinegar butter garlic rosemary salt and mustard. Bring to a boil then pour sauce over chicken.

Bake in a preheated oven for 30 minutes. Turn chicken breasts over and continue baking until done about 20 to 30 minutes.