In a medium size mixing bowl, mix together flour, sugar, baking powder, baking soda, and salt.
In a seperate bowl, whisk together egg yolks, cream, buttermilk, melted butter, and vanilla.
Whisk the wet ingredients into the dry, just until combined-it's okay if there are a few lumps.
Preheat and lightly grease a heavy skillet or griddle. Scoop the batter onto the griddle with a 1/4 cup measure or large spoon. Make sure the heat is slightly less than medium. The pancakes will puff up very high. When the first side is golden brown and the edges start to look dry, turn pancakes over to finish cooking the second side.