Heat a griddle over medium heat and cover with a thin layer of neutral oil. In a medium bowl, whisk together flour, sugar, salt, soda, and baking powder.

In another medium bowl, lightly beat the egg yolks, then whisk in the butter, buttermilk, and milk.

Add the buttermilk mixture to the dry mixture and stir gently until barely combined.

Add lightly beaten egg whites to the mixture and gently stir until a thick, lumpy bumpy batter forms. Stop before the batter smooths out. Lumpy batter is good!

Drop quarter cups of batter onto the preheated pan. Cook until bubbles start to appear on the exposed surface of the pancake. When bubbles appear, flip pancake and cook for an additional 2-3 minutes or until browned. Remove to a wire rack and allow to cool. Repeat with remaining batter.

Grease a 9 x 13 inch casserole dish. Cut the pancakes in half (you should have around 20), and layer them cut side down in the pancake dish.

In a large bowl whisk together the eggs, milk, cream, vanilla, and sugar. Pour evenly over the pancakes.

Cover with saran wrap and refrigerate pancakes overnight.

In the morning, preheat the oven to 350 degrees. Whisk together the flour, oats, pecans (optional), brown sugar, salt, and cinnamon. Pour the melted butter over top and stir. Use your fingers to work the mixture until crumbs form. (Note: You can do this step the night before, and store it in a bowl in the refrigerator if you prefer.) Pour the crumbs evenly over the top and bake for 45-50 minutes or until the crumbs are browned and center is set.