Pumpkin French Toast Sandwiches

1. Liberally spray a 9 x 13 baking dish with cooking spray. Lay half of the slices of bread in a single layer in the bottom of the pan. In a bowl, stir together the softened mascarpone cheese, balsamic vinegar, vanilla and pumpkin pie spice. Evenly distribute the mascarpone mixture onto each slice of bread and smooth it out. Finish each sandwich with another slice of bread on top.
2. In a mixing bowl thoroughly whisk together the milk, pumpkin butter, eggs, vanilla, pumpkin pie spice, cinnamon and nutmeg. Pour the custard all over the sandwiches and make sure they get pretty submerged by gently pressing down on the sandwiches. Cover the baking pan and let it sit in the refrigerator overnight.
3. In the morning, preheat the oven to 350 F. Remove the dish from the fridge and remove the cover. Get the pan of custard-soaked sandwiches into the oven to bake for 45-50 minutes, until the bread is golden and crisp on the edges and the egg mixture is set. Take it out of the oven and let it cool for a couple of minutes.
4. Cut out and plate each sandwich with all of that gorgeous custard on it. Dust the top of each sandwich with powdered sugar and serve!