Butter 6 individual gratin dishes. Preheat oven to 375 degrees and set a rack in the middle level. Toss peaches with water and extract and divide among the dishes. For the topping, melt the butter and stir in the remaining ingredients in order. Crumble the topping over the individual dishes. Bake the gratins about 30 minutes, until bubbling and the topping has colored. Cool to room temperature and serve with whipped cream or Creme Fraiche.