Lightly spoon flour into dry measuring cups, and level with a knife.
Combine flour and next 6 ingredients (flour through nutmeg); cut in chilled butter with a pastry blender or 2 knives until mixture resembles coarse meal.
Combine buttermilk and pumpkin; add to flour mixture, stirring just until moist. Turn the dough out onto a lightly floured surface; knead lightly 5 times.
Roll dough to about 1/2-inch thickness.
Cut into 12 biscuits with a 2 1/2-inch biscuit cutter.
Place the biscuits on a baking sheet coated with cooking spray.