Melt the brown sugar and butter in a saucepan over medium heat. Allow to boil and quickly reduce heat to simmer. Remove from heat and pour into a well-greased 9x13 pan, making sure it is spread evenly.
Cut/cube the pears and arrange evenly on top of the brown sugar mixutre. Sprinkle the French bread pieces over the pears. Cube the second pear and place on top.
Beat eggs, milk, vanilla together and pour evenly over the entire mixture. Press bread lightly into egg mixture to avoid dryness and to soak up all the eggs/milk. Cover and refrigerate overnight.
Preheat oven to 350. Bake uncovered for 40 minutes, or until it becomes puffy and the eggs are no longer runny.
Sprinkle nuts and dust with powdered sugar; serve!