Preheat oven to 450°. In a large bowl, whisk flour, baking powder, sugar, salt and cream of tartar. Cut in butter until mixture resembles coarse crumbs. Stir in cheese, garlic and pepper flakes. Add milk; stir just until moistened., Drop dough by heaping 1/4 cupfuls 2 in. apart onto a greased baking sheet. Bake 18-20 minutes or until golden brown. Serve warm.