Preheat oven to 350F, spray a 9x13 dish with some cooking spray.
Open both rolls of biscuits and cut all 20 biscuits into 6 small pieces each, giving you 120 pieces of dough.
Mix your 1 Tbsp of sugar and heaping tsp of cinnamon in a bag large enough for you to add the dough pieces too and shake, making sure to cover all of the pieces. The pieces will clump together so be sure to separate them while shaking the cinnamon sugar onto them.
Place the dough pieces in your dish to cover the bottom evenly.
In a bowl or pyrex measuring cup whisk your eggs and milk together, stir in vanilla and cinnamon.
Pour egg mixture over your dough pieces. Bake in the oven for 35 minutes.
Remove from oven, you can now mix your icing sugar, milk and vanilla together and pour over the french toast bake while it is still warm.
Let icing set and then cut into 12 equal servings.