Preheat oven to 375 degrees. Sift flour, sugar, baking powder and salt into large mixing bowl. Add butter and rub in with fingertips until mixture resembles coarse meal. Gradually add buttermilk, tossing with fork until large moist clumps form. Add parmesan and sage; combine.
Gather biscuit dough into a ball and roll out onto a surface that has been dusted generously with flour. Cut into 3-inch rounds and transfer onto a baking sheet that has been lined with parchment paper.
Bake biscuits until toothpick inserted into center comes out dry, about 20 minutes (biscuits will be pale). Transfer biscuits to rack and cool to lukewarm.