Cut bread into 1 inch cubes and place in a greased 9x13 inch casserole dish.Prepare the topping by combining brown sugar, flour, cinnamon and salt in a bowl and whisking to distribute ingredients well. Cut butter into small cubes and add to dry ingredients. Mash in with a fork or pastry cutter. Stir in chopped pecans. Cover and place in fridge.In a medium bowl whisk together milk, eggs, vanilla, sugar, and cinnamon. Pour over bread in the casserole dish. Cover and chill overnight.Next morning preheat oven to 350 degrees. Uncover topping bowl and casserole dish. Sprinkle topping over the soaked bread mixture. Bake uncovered for 35-45 minutes until golden and bread is baked through.Drizzle with syrup or sprinkle with powdered sugar and serve warm.