Preheat oven to 375.
Slice chicken breasts partway through for stuffing, finely chop mushrooms and onion.
In small skillet, sautee onions in butter and brown sugar until caramelized. Set aside in bowl.
Fry bacon in large skillet, remove and sautee mushrooms in bacon fat.
Chop bacon and mix with onion, sage, 1 tbsp maple syrup and strained, cooked mushrooms.
Stuff chicken, flour lightly and brown in remaining bacon grease.
Arrange chicken in baking pan. Mix together 3 tbsps maple syrup with water and pour over chicken.
Bake for 25-30 minutes, turning once. Add more water/syrup if pan is drying up, to prevent burning.
Serve with reheated, leftover stuffing spooned on top each breast and drizzle with sauce from pan and maple syrup.
Mashed potatoes or colcannon are a good complement - spoon sauce over potatoes as well.