Preheat oven to 400℉
Mix the Einkorn Flour, Baking Powder, Sugar, and Salt together in a medium bowl.
Take butter directly out of the refrigerator and grate it into the Einkorn Flour mixture.
Cut to Butter into the Flour mixture with a fork or pastry blender. **COLD butter is the key to flaky biscuits, so mixing with a fork or pastry blender keeps the butter colder than cutting it in with your hands. If you prefer to use your hands, pop the mixture back into the fridge for a few minutes to cool everything back down.** The goal here is a coarse texture. There will still be larger bits of butter, but that is ok.
In a separate measuring cup, add the Apple Cider Vinegar to the Whole milk. Stir to combine, and the let sit for a minute so the milk has a chance to thicken up.
Add the Milk mixture to the Flour mixture and stir until just mixed. Take care not to over stir. Biscuits are kind of like pie crust, in that you want to touch/work the dough as little as possible.
Lightly flour a piece of parchment paper, or your counter. Pat dough out into roughly 5" x 10" rectangle, about 3/4"-1" thick - The size isn't as important as the thickness, so don't get caught up on the dimensions. Cut horizontally into (4) 2½" x 5" sections, then divide each of those into (2) 2½" squares. **Take care not to "saw" the dough as you divide it. Simply push down on your knife and make ONE cut. "Sawing" will bind the edges of your biscuit, preventing it from rising to its full potential.** You will end up with (8) 2½" x 2½" squares.
You can push the corners a bit, rounding them out, creating more oval biscuits.
Transfer biscuits to a parchment lined baking sheet and pop into the preheated oven. Bake for 20 minutes.
Remove from oven. Enjoy!