Be sure to mix the pancake batter the night before you are wanting to serve. Add the yeast to warm buttermilk and let sit five minutes. Meanwhile, in a medium mixing bowl mix together all the dry ingredients, except the yeast. Stir in the buttermilk/yeast mixture, melted butter, and vanilla. Cover the batter with plastic wrap and place in the refrigerator overnight. The next morning heat a griddle or skillet over medium heat. Mix the eggs into the batter. The batter will have raised and thickened overnight. Use a whisk and mix until smooth. Spoon batter into and cook until edges are dry and bubbles pop in the middle. Flip over and cook just until the other side is golden. {The more batter, the larger your pancake.}