In a large skillet, melt butter; add onion, cabbage & garlic. Cook, stirring frequently, until vegetables are crisp-tender, about 5-7 minutes. Add water, cover & cook for 5 minutes. Remove cover & cook until liquid evaporates & cabbage begins to brown, about 8-10 minutes longer. It is important to get the liquid out of the cabbage or it will cause quiche to become watery.