In a large mixing bowl, combine the flour, baking soda, salt, and sugar. In a smal bowl, beat the eggs. Add the buttermilk, butter, and vanilla and mix thoroughly. Gradually add the egg mixture to the dry ingredients and stir until well combined. Fold in the apple and nuts. Allow the mixture to stand for 15 minutes.
Drop a scant 1/4 cup batter onto the griddle. Bake until the surface of the pancake is covered with bubbles that do not break, about 2 to 3 minutes. Turn and brown the other side.