01 - Grease a 9x13-inch baking dish generously with cooking spray or softened butter, ensuring all surfaces are well coated.
02 - Layer the pancakes evenly across the bottom of the prepared dish, overlapping them slightly to create a uniform base. Brush the surface 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 sausage or bacon crumbles, shredded cheddar cheese, and fresh berries (if using) evenly over the pancake layer.
05 - Slowly pour the egg custard over the pancakes and add-ins, tilting the dish gently to ensure even coverage throughout.
06 - Cover the dish tightly with plastic wrap or aluminum foil and refrigerate for at least 4 hours, ideally overnight, to allow the pancakes to absorb the custard.
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 before baking.
09 - Bake uncovered for 40 to 45 minutes until the top is golden brown, the center is puffed, 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 additional fruit if desired. Serve warm.