In a medium size bowl, toss together the whey, almond flour, baking powder, baking soda, cinnamon (if using), and salt. Set aside.
In a small bowl, whisk together the milk and the egg. Add the melted butter, vanilla, and liquid stevia and whisk again until everything is combined. Pour the wet ingredients into the dry ingredients and whisk again until ingredients are just combined.
Heat a griddle or skillet over medium-low heat. Coat generously with butter, vegetable oil, or coconut oil. Once hot, drop ¼ cup of batter onto the skillet. Cook until bubbles begin to form on the edges. Center will still be very wet. This is ok. Using a large spatula, flip the pancake quickly and cook on the other side until cooked through. Coat griddle/skillet again with choice of fat for each pancake.
Pancakes are best served immediately with your favorite toppings. Pancakes can be reheated in the microwave as needed (wrapped in a moist paper towel) or kept warm in a 200ºF oven until all pancakes are ready to serve. Leftover pancakes can be kept in the refrigerator, wrapped tightly in plastic wrap, up to 3 days. Pancakes can be frozen, up to 2 months. Reheat as desired.
*You can make your own almond flour by processing whole almonds in a food processor. Pulse until a fine powder forms.