3 cups all-purpose flour
1/3 cup sugar
1 teaspoon salt
2 1/2 teaspoons baking powder
1/2 teaspoon baking soda
3/4 cup unsalted butter, very cold and cut into 1/2 inch pieces
1 cup buttermilk (or more)
Put dry ingredients in food processor, pulse to mix.
Add butter, pulse until butter is in pieces about the size of a hazelnut.
Dump into bowl.
Pour in buttermilk and mix with a fork until a shaggy mass forms.
Form into a disk about 1 1/2 inches high, cut disk in half and in half again.
Cut each of the 4 pieces either into thirds to get 12 or in half again to get 8.
Place on parchment lined sheet pan and freeze for 20 minutes Remove from freezer, brush tops with egg yolk/cream mixture sprinkle with sugar.
Bake for about 12 minutes at 400.