Melt butter, Karo syrup and brown sugar over medium heat. Bring to a boil, add 2 tablespoons water. Continue boiling until thick and frothy. Pour mixture into a 9x11 inch greased baking dish. Slice peaches and lay in pan (6 across and 3 deep). Lay bread over peaches.
Mix eggs, milk and vanilla and pour over bread. Sprinkle with cinnamon and cover. Refrigerate overnight. Uncover, sprinkle with pecan pieces and bake in 350 degree oven 45-50 minutes, until brown. Serve with peach-laced syrup and powdered sugar.