Combine first 3 ingredients in a small, heavy saucepan over medium heat. Cook 5 minutes or until bubbly and sugar dissolves, stirring constantly. Pour sugar mixture into bottom of a greased 13 x 9-inch baking dish. Spread mixture evenly over bottom of pan. Chop pecans and scatter on top of sugar mixture. Set aside.
Combine milk and next 5 ingredients (through eggs) in a large shallow bowl; stir with a whisk. Dip bread slices in milk mixture; arrange bread slices over sugar mixture in dish. Pour any remaining egg mixture over bread slices. Cover and refrigerate overnight.
In the morning, preheat oven to 350°, and bake for 30 minutes. To serve, dish out slices with a spatula and turn upside down (caramel side up). Serve with butter or dusted with powdered sugar or just as it is.
Recipe by Sprung At Last at https://sprungatlast.com/2012/12/simple-french-toast-casserole/