Light outdoor grill to medium temperature. Grill frozen turkey burgers until done, approximately 7-8 minutes per side.
Remove from grill. Slice in half to make two thin patties.
Heat up waffle maker. Spread butter on one side of bread slices. Lay butter side down, and layer the turkey burgers, avocado, cheese, and tomato. Top with other slice of bread, butter side up.
Place sandwiches in waffle maker, and grill until brown on all sides.