Preheat the oven to 350 degrees F. Butter a baking sheet.
Whisk the bread flour, cake flour, baking powder, sugar and salt in a large bowl. Work in the shortening with your fingers until the mixture is combined. Beat the eggs and buttermilk, then stir into the flour mixture with a fork to make a shaggy dough.
Turn the dough out onto a lightly floured surface and roll out to 1/4 inch thick.
Cut out biscuits using a 2 1/2-inch-round cutter or glass, rerolling the scraps as needed.
