Cinnamon Roll French Toast Casserole

0 Chop bread into cubes. If bread is not slightly stale or a day old, bake at 350 for 10 minutes on a baking sheet till slightly dried. 
1 Grease a 9x13 baking pan.
2 In a large bowl add cream, butter, sugar , milk, eggs, vanilla, cinnamon. Whisk till well combined. 
3 Add bread to the baking dish in an even layer. Pour custard evenly over the bread.
4 Let sit covered for 1 day in the fridge to let the bread soak up the custard. 
9 In a bowl combine all the topping ingredients and mix till smooth.
10 Sprinkle over top of the casserole in a even layer.
5 Bake at 350 degrees for 25 minutes. Then cover and bake for another 35 minutes until French toast is set and bread is golden. Can bake for another 5-10 uncovered to get the topping nice and crisp.
6 In a bowl beat all the frosting ingredients together until smooth and set aside.
7 Slice the casserole and pour over the frosting when ready to serve. 
8 Keep leftovers in fridge for 3-5 days.