Step 1 Heat oven to 375 degrees.
Step 2 In a food processor bowl, pulse together the flour, granulated sugar, baking powder, salt and orange zest. Add the cold cubed butter and the egg yolks and pulse together just until the mixture has the texture of lightly moistened cornmeal. There may be a few pea-sized chunks of butter remaining; that's fine.
Step 3Pour over 3/4 cup heavy cream and then pulse 4 to 6 times just to moisten the dough. Do not overmix or the dough will be tough.
Step 4Turn the dough out onto a lightly floured work surface and gather into a shaggy mass. Knead 3 to 4 times to make it cohesive and then pat into a rough circle 6 to 7 inches in diameter and a fairly consistent 3/4 to 1 inch in thickness.
Step 5Using a sharp knife, cut the circle into 6 wedges. Brush the tops very lightly with heavy cream (there should be enough left in the measuring cup) and sprinkle lightly with the coarse sugar.
Step 6Transfer to a cookie sheet and bake until risen and golden brown, 18 to 20 minutes. Turn the pan around halfway through to ensure even cooking. Remove to a cooling rack.