In small bowl, combine butter and cinnamon and spread over each slice of bread.Place 6 slices butter side up in greased 15x9 inch baking dish, a glass dish is best. Sprinkle with 1/2 of brown sugar. repeat layer.
In large bowl, whisk eggs, milk, syrup and vanilla, pour over bread. Cover and refrigerate overnight.
Remove from refrigerator 30 minutes before baking. Bake uncovered @ 350 for 40-50 minutes or until golden and puffed. Serve with syrup.