Pour vinegar or lemon juice into milk and let sit for 5 minutes.
Meanwhile, mix the dry ingredients together in a bowl: whole wheat flour, all purpose flour, Splenda, baking powder, baking soda, salt, and nutmeg.
Stir the milk/ vinegar mixture, then mix in the egg whites, oil and banana.
Pour the liquid mixture into the dry mixture and stir until just blended. It is important to not overmix at this point. If the batter seems too thick, add more milk to thin it a bit.
Heat a griddle or frying pan to medium heat. Grease the griddle or pan with a little butter or cooking oil and add 1/4 cup batter to pan. Place several blueberries on the pancake. Cook on medium-low to medium until golden to medium brown, the edges appear dry, and bubbles begin to appear on the surface. Flip and cook until the second side is golden brown (the second side will cook much faster).
You can keep the pancakes warm by placing them on a heat-proof plate and keeping them in the oven at 175F until all the pancakes are completed. Serve these with butter, sliced banana, and syrup if desired.