01 - Grease a 9x13-inch baking dish generously with cooking spray or softened butter, ensuring all surfaces are coated to prevent sticking.
02 - Arrange the pancakes in the prepared baking dish in a single even layer, overlapping slightly where necessary. Brush the tops evenly with the melted butter.
03 - In a medium mixing bowl, whisk together the eggs, whole milk, heavy cream, salt, black pepper, cinnamon, and vanilla extract until fully combined and smooth.
04 - Scatter the desired add-ins — sausage or bacon crumbles, shredded cheddar cheese, and/or fresh berries — evenly across the pancake layer.
05 - Slowly pour the egg custard mixture over the pancakes and fillings, tilting the dish gently to ensure even coverage throughout.
06 - Cover the baking dish tightly with plastic wrap or aluminum 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 baking dish from the refrigerator, uncover it, and let it stand at room temperature for 15–20 minutes while the oven comes to temperature.
08 - Drizzle 2 tablespoons of maple syrup evenly over the top of the casserole just before baking.
09 - Bake uncovered for 40 to 45 minutes until the top is golden brown, the center is puffed and set, and a knife inserted in the middle comes out clean.
10 - Allow the casserole to rest for 10 minutes before slicing into portions. Dust with powdered sugar and garnish with fresh berries or sliced bananas if desired. Serve warm.