Line a rimmed baking sheet with parchment paper. Set aside.
Cut butter into small 1/2-inch cubes and place on a plate back in the refrigerator until later.
In a liquid measuring cup (or medium bowl), whisk together 1 1/3 cup buttermilk and vanilla extract. Set in the refrigerator.
In a large mixing bowl, whisk together the flour, sugar, baking powder and salt.
Remove the cold cubed butter from the fridge and add it to the dry ingredients. Toss until each butter cube is coated in flour.
Use a pastry cutter to cut the butter into the dry ingredients until it resembles breadcrumbs. *Alternatively, use your hands to pinch each piece of butter between your thumb and pointer finger and shingle it into a flat piece, then toss back in the flour to coat and break it up into smaller pieces. Repeat with remaining butter until it all resembles breadcrumbs.
Remove the buttermilk mixture from the fridge and slowly pour it over the butter-flour mixture and use a rubber spatula to mix everything together until a dough begins to form.
Dust the counter with 2 tablespoons of flour and place the dough on top. Push the shaggy dough together to form one mass, then press it into a large rectangle.
Use your fingers and palms to flatten the dough into a large rectangle. Fold into an envelope. Shape and press down again to a large rectangle. Repeat this 2 more times. You can use a rolling pin or your hands for this step.
Finally, dust the counter again with flour and shape the dough into a 8”x8” square or circle. It should be about 1 inch in thickness.
Use about a 2 1/2 inch biscuit/cookie cutter to cut round biscuits and place onto the prepared baking sheet, at least 2 inches apart.
Set the pan of biscuits in the fridge and chill for 15 minutes while you preheat the oven to 375 degrees F.
Brush each biscuit with the remaining 2 tablespoons of buttermilk and sprinkle with coarse sugar.
Bake for 5 minutes at 375 degrees F, then reduce the temperature to 350 degrees F and bake for another 12-15 minutes, or until the biscuits are puffed and golden.
Let biscuits cool on the pan for 10 minutes before transferring to a wire cooling rack to finish cooling completely.
Store in a ziplock bag until ready to eat!