Cream the butter and the sugar together in a large bowl.
Add the egg yolks (not the whites, which should be in their own bowl) and the vanilla. Mix well.
Sift the flour, salt, spices, and baking soda onto parchment paper or a flexible cutting board.
Add the flour and buttermilk, half of each at a time.
Stir together. You will have a very thick batter.
Whip the egg whites in their bowl until soft peaks form. Then, gently fold them into the batter with a spatula.
Scoop into muffin trays to bake. Bake at 350 for 20 - 25 minutes, until golden brown and springy.