Grease a 9 X 13 inch baking dish.
Stir Member's Mark™ Light Brown Sugar and butter together in a saucepan over medium-low heat for 2-4 minutes, until the butter is melted and brown sugar has dissolved.
Pour brown sugar-butter mixture into the prepared baking dish. Scatter crusty French bread pieces over the top evenly.
Whisk milk, eggs, and vanilla together in a bowl until well combined. Pour mixture over bread pieces, then press down on the bread with a spatula so it absorbs the mixture. Cover the dish with plastic wrap and refrigerate 8 hours to overnight.
When ready to bake, preheat the over to 450 degrees. Remove french toast from the refrigerator and discard plastic wrap.
Sprinkle Member's Mark™ Cinnamon over the french toast.
Bake in preheated oven for 30 minutes, or until the casserole is browned and bubbling.
Once done cooking, cut the casserole into squares and serve!