Overnight Banana Caramel French Toast

Spray a 9x13" glass baking dish with non-stick spray. Layer 1/2 of bread in baking dish. Top with bananas and caramel. Then top with the rest of the bread. Whisk together eggs, milk, heaving whipping cream, cake mix, cinnamon and vanilla extract in a large bowl. Pour mixture over bread. Cover baking dish and store in the fridge overnight or for several hours. Preheat oven to 350 degrees. For the topping in a small bowl add flour, brown sugar, cinnamon and salt, stir until combined. Cut in butter to mixture. Remove french toast casserole from fridge, uncover and drop topping by the spoonful randomly across french toast casserole. Bake for 1 hour until the center is set and edges are browned. Serve with syrup if desired.