01 - Grease a 9x13-inch baking dish generously with cooking spray or softened butter, ensuring all surfaces are evenly coated to prevent sticking.
02 - Layer the pancakes in the prepared baking dish, overlapping them slightly to create an even surface. Brush the tops 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 — crumbled sausage or bacon, shredded cheddar cheese, and/or fresh fruit — evenly across the pancake layer.
05 - Slowly and carefully pour the egg custard mixture over the pancakes and add-ins, tilting the dish gently to ensure everything is evenly coated and saturated.
06 - Cover the baking dish tightly with plastic wrap or aluminum foil and refrigerate for a minimum of 4 hours, ideally overnight, to allow the custard to fully absorb 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 while the oven comes to temperature.
08 - Drizzle 2 tablespoons of maple syrup evenly over the surface of the casserole before baking.
09 - Bake uncovered for 40 to 45 minutes until the top is golden brown, the center is puffed and firmly 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 fruit as desired. Serve warm.