First, preheat the oven to 415° and line a baking sheet with parchment paper.
In a medium mixing bowl, sift together the flour, baking powder, sugar, cream of tartar, and salt.
Using a pastry blender or your hands, cut in the butter until the flour resembles coarse crumbs. Then add the milk and stir with a fork until the mixture comes together.
On a lightly floured surface, pull out the dough and knead until it's smooth.
Divide the dough in half, and roll out the first half until it's about ½ inch thick. Cut circles from the dough using a cookie cutter, and arrange them on the prepared baking sheet. With the remaining dough, reform and roll out to ½ inch and repeat until all the dough is used. Repeat this process with the other half of the dough too.
Bake the biscuits for 10-12 minutes, or until risen and a golden brown.
Remove from the oven and brush the tops with melted butter. Serve warm and enjoy.