Sift together the flour, baking powder, sugar, and salt in a large bowl. Stir in the orange zest. Add the cold butter to the flour mixture and, using a fork or pastry blender, cut the mixture until it resembles coarse meal. In another bowl, mix together the cream and buttermilk and add all at once to the dry ingredients.
Stir the dough with a rubber spatula just until it is moistened. Turn out onto a floured board and pat out to a 3/4-inch-thick rectangle. Using a 3-inch biscuit cutter, cut into rounds. Place the rounds 1 inch apart on a baking sheet. Bake for 20 minutes, or until puffed and lightly browned.