01 - Grease a 9x13-inch baking dish with cooking spray or butter, ensuring even coverage on all surfaces.
02 - Arrange the pancakes in the prepared dish, overlapping them slightly to create a uniform base. Brush the tops evenly with the melted butter.
03 - In a medium mixing bowl, whisk together the eggs, whole milk, heavy cream, salt, pepper, cinnamon, and vanilla extract until fully combined and smooth.
04 - Scatter the desired add-ins — sausage or bacon, shredded cheddar cheese, and/or fresh fruit — evenly across the pancake layer.
05 - Slowly pour the egg custard mixture over the pancakes and add-ins, tilting the dish gently to ensure even coating throughout.
06 - Cover the dish tightly with plastic wrap or foil and refrigerate for at least 4 hours, preferably overnight, to allow the custard to soak into the pancakes.
07 - Preheat the oven to 350°F. Remove the dish from the refrigerator, uncover it, and let it stand at room temperature while the oven comes to temperature.
08 - Drizzle the maple syrup evenly over the top of the casserole.
09 - Bake uncovered for 40 to 45 minutes, or until the top is golden brown, puffed, and the center is fully set with no liquid visible.
10 - Allow the casserole to rest for 10 minutes before slicing into portions. Dust with powdered sugar and top with additional berries or sliced bananas if desired. Serve warm.