This is a unique twist among the many versions of French Toast.
In a small pan, cook frozen cranberries with about 2 Tbsp. of the brown sugar and 1 tsp. Grand Marnier until tender. Set aside.
Peel and dice apples and pears and sauté in butter over medium heat with brown sugar, cinnamon, and nutmeg, for about 5 minutes. Add 1 Tbsp. Grand Marnier and maple syrup. Continue cooking, stirring often, until tender. Fruit will release some juice during cooking. Be sure to keep this to spoon over croissants with the fruit. Remove from heat, add cranberries and stir. Fruit topping can be made ahead and refrigerated, then reheated before serving.
Mix all ingredients for batter. Use a sharp serrated knife or scissors to cut a small piece off the top of each croissant. Dip each croissant into batter, and allow excess batter to run off. Cook croissants on a griddle or in a skillet as you would French Toast, browning on both sides. Remove from heat, and spoon cooked fruit and juice over the top. Sprinkle with powdered sugar and serve immediately. Serves 12.