2 cups flour
2 tablespoons white vinegar
2 cups plus 1 1/2 tablespoons whole milk
1 tablespoon vanilla extract
1 1/4 teaspoons baking powder
2 1/2 tablespoons unsalted butter plus more for the pan
1/4 teaspoon salt
4 tablespoons sugar
1 teaspoon cinnamon
2 large egg yolks
3 large egg whites
Put the vinegar in a large, liquid measuring cup. Add the cold milk and let rest until it reaches room temperature. Melt the butter in the microwave and let it rest until it reaches room temperature.
Sift together the dry ingredients through a fine, mesh sieve. Repeat the process twice more into a large glass or ceramic mixing bowl. Avoid a metal mixing bowl! Pour the milk and vinegar mixture over the dry ingredients slowly while whisking. Stop adding milk when the mixture resembles a natural yogurt.
While whisking, slowly add the melted butter until well combined. Keep whisking and add the two egg yolks one at a time until combined. Add the vanilla extract and whisk until combined, then stop. Let the mixture rest for 5 to 6 minutes.
Preheat the oven to 350F. While the mixture is resting, vigorously whisk the egg whites until fluffy and they begin to form medium peaks. Gently fold the egg whites into the batter using a wooden spoon or a plastic spatula, again avoiding metal so you don’t interfere with the egg whites.
Melt 1 tablespoon of butter in an oven-safe skillet over medium heat. Swirl to coat the sides. Pour 1/2 cup of batter into the pan and cook on the stove for one minute, then transfer the pan to the oven and bake for 3 minutes. Flip the pancake and place back into the oven for two or three more minutes until cooked through. Transfer the pancake to a serving platter, add more butter as necessary, and repeat with the remaining batter.
Serve with toppings.