Grease 9x13" baking dish. Set aside.
Cut bread into cubes and set aside.
Melt butter over medium high heat in large skillet until melted.
Add 3/4 cup brown sugar, 1 teaspoon cinnamon and 1 teaspoon vanilla.
Stir until mixture thickens a little, then add apples and stir until coated.
Remove from heat and set aside (let cool).
In a large bowl, beat eggs.
Beat in remaining brown sugar, cinnamon and vanilla.
Add nutmeg, half and half and milk.
Whisk until blended.
Add bread cubes and gently stir until bread has soaked up liquid.
Pour bread mixture into prepared baking dish.
Pour apple mixture over bread mixture.
Cover with plastic wrap and refrigerate overnight.
Preheat oven to 350.
Remove plastic wrap and bake for 35 minutes.
In a bowl whisk together flour, cinnamon, nutmeg and brown sugar for streusel.
Cut in butter using a fork until crumbly.
Sprinkle mixture over top of baking dish.
Return to oven for 25-30 minutes until streusel is browned.