Preheat the oven to 450 degrees F. and line a baking sheet with parchment paper. In a medium bowl, whisk together 3 cups all-purpose flour, 4 teaspoons baking powder, 2 tablespoons granulated sugar, ¾ teaspoon cream of tartar, and ½ teaspoon salt. Set this dry mixture aside.
In a separate small bowl, whisk together the 1 large egg and 1 cup milk until combined.
Using a fork or pastry cutter, cut the cold butter into the flour mixture until it resembles a coarse meal and the butter is about the size of a pea.
Next, add the milk/egg mixture into the flour mixture using a wooden spoon to stir just enough until it comes together to form a loose dough ball.
Roll the dough into a loose ball, lightly flour a clean work surface.
Using a lightly floured rolling pin, roll out the dough and cut the biscuit shapes using a biscuit cutter. Place the cut biscuits onto the prepared pan and place them into the oven to bake for 10 to 15 minutes, until golden brown.
Once finished, carefully remove the biscuits from the oven. Brush the top of each biscuit with additional butter if you prefer and serve immediately while still warm. Enjoy!
Store any leftover biscuits in an airtight container at room temperature for 2 days or in the refrigerator for up to 4 days.