Preheat oven to 450 degrees F and grease a baking sheet.
In a bowl, whisk together flour, baking powder, baking soda, and salt.
Using a pastry blender (or fork), cut the butter into the flour mixture until the butter is in crumbles.
Pour in the buttermilk and mix, just until combined.
Transfer onto a floured surface and roll out to about 1/2 inch thickness.
Using a circle cookie cutter, cut out biscuits and place on the greased cookie sheet.
Re-roll the scraps and cut out again, until dough is gone. Use the egg wash to brush on top of the biscuits.
Bake for about 15 minutes, or until golden brown on top. Enjoy!
