In a medium sized bowl beat together eggs, half and half, vanilla and sugar; set aside. Mix together in a small bowl brown sugar and cinnamon. Spray a 9 X 17-inch baking dish with vegetable spray and place 6 slices of bread in bottom of casserole dish. Sprinkle with half of brown sugar mixture and top with half of pecans. Pour half of egg batter mixture over bread, pressing liquid into bread slices. Place remaining bread slices on top and repeat layers. Press liquid into bread slices to make sure all edges are covered. Refrigerate overnight. Bake in a 350 F oven for 40-45 minutes or until French Toast is puffy. In a small bowl combine powdered sugar and milk; using a wire whisk beat until smooth. Drizzle glaze randomly over top of toast.