Preheat the oven to 350°. Heat griddle to medium high heat about 350°.

Whisk eggs, milk, vanilla, and cinnamon together until well blended. Pour into a shallow bowl or pie plate.

Put sliced bagels into the egg mixture, allowing bagel to soak up some of the mixture. Coat griddle with butter and add as many sliced bagels on to the griddle as will fit. Fry until brown on both sides.

Place the cooked French toast on a sheet pan and repeat until all the bagels are browned. Place the baking sheet in the preheated oven and bake for 5-7 minutes until bagels are cooked through. Serve with butter, powdered sugar and maple syrup.