Pre-Heat Oven to 425 degrees

1. In a small bowl, mix together milk and vinegar and let sit while preparing the rest of the ingredients.
2. In a medium bowl, mix flour, baking powder, baking soda, and salt. Using a pastry knife cut in cold butter until it resembles bread crumbs.
3. Make a well in the flour mixture and pour in the milk mixture. Mix until just combined. DO NOT over-mix. (If the mixture is too dry then add the additional tablespoon of half-and-half)
4. Pour the mixture out onto a floured surface and pat it into a rectangle. Fold the rectangle in thirds, like you are folding a letter. Rotate the dough by 90 degrees and roll the dough until it doubles in size. Fold the dough in thirds again. Repeat this process one more time. Then roll the dough until it is about ½-inch thick.
5. Using a round biscuit cutter, cut the biscuits and place them onto a parchment paper-lined cookie sheet. Re-roll the scraps until you have used all the dough. Brush the tops with egg wash.
6. Bake for 12-15 minutes or until golden brown.