I got this recipe off the internet and changed it to work for my taste and altitude.
1 egg beaten
In a large mixing bowl sift the flour with baking powder, salt, and baking soda. Cut into flour mixture the butter with a pastry blender until well blended. Butter should be cold to start and it should look like very small bits when blended into flour. Add one cup of buttermilk and stir. If the dough is dry add the rest of the buttermilk. Mix until slightly blended. Turn out on lightly floured board or counter top and kneed for about two minutes or until dough is mixed well enough to form large ball. Roll out to about 1 inch thick and cut with round biscuit cutter or with a small juice glass that is greased around the edges. Place on a cookie sheet and brush with pastry brush the tops of the biscuits with beaten egg. Bake at 350 degrees F for 18 to 22 minutes. Serve warm.