Preheat the oven to 350 degrees.
Spread melted butter over the bottom of a 9x13in pan.
Cut cinnamon rolls each into 6 pieces.
Spread cinnamon roll pieces evenly in the prepared pan.
In a separate bowl, combine eggs, milk, cinnamon and vanilla. Stir until combined.
Pour egg mixture evenly over the cut cinnamon roll pieces.
Bake in preheated oven for 30-35 minutes until the top is golden and the centers are fully cooked.
Allow to cool for about 5 minutes.
Spread reserved cinnamon roll icing over the top of the french toast casserole.
Serve with fresh berries and syrup.