Preheat oven to 450°F. In a large bowl combine flour, baking powder, sugar, salt, and cream of tartar.
Test Kitchen Tip: If baking powder or cream of tartar appears lumpy, sift through a fine-mesh sieve before using.
Using a pastry blender, cut in butter and shortening until mixture resembles coarse crumbs.
Make a well in the center of the flour mixture. Add milk all at once. Using a fork, stir just until mixture is moistened.
Turn dough out onto a lightly floured surface. Knead dough by folding and gently pressing it for four to six strokes or just until dough holds together.
Pat or lightly roll dough until ¾ inch thick. Cut dough with a floured 2½-inch biscuit cutter; reroll scraps as necessary and dip cutter into flour between cuts.
Place dough circles 1 inch apart on an ungreased baking sheet. If desired, brush with additional milk for browning. Bake 10 to 14 minutes or until golden. Remove biscuits from baking sheet and serve warm.
Test Kitchen Tip: Biscuits don't have to be round. You could also cut biscuits with a square cutter, or roll the dough into a rectangle and cut it into strips or squares. Or roll the dough into a circle and cut into wedges. Just always aim for 12 biscuits so the bake time doesn't need adjusting.
Drop Biscuits Variation:
Cut the prep time of this recipe almost in half by skipping the kneading, rolling, and cutting steps. Prepare as above through Step 3, except increase the milk to 1¼ cups. Using a large spoon, drop dough into 12 mounds onto a greased baking sheet. Bake as directed above. Makes 12 biscuits.
Buttermilk Biscuits Variation:
Prepare as above, except for rolled dough biscuits substitute 1¼ cups buttermilk or sour milk for the 1 cup milk. For drop biscuits substitute 1½ cups buttermilk or sour milk for the 1¼ cups milk.
