Note: Sanding sugar is coarser than granulated sugar and lends a lovely sparkle when sprinkled over the tops of scones, biscuits, pies, and cookies before baking. It is available at baking-supply stores and many grocery stores.
Pour 2 cups cream into the flour mixture. Using your hands, draw the dry ingredients over the cream, gradually gathering and combining the dough until it just comes together. If it is too dry, add more cream, 1 tablespoon at a time.
Turn out the dough onto a lightly floured work surface. With lightly floured hands, gently press and pat the dough into an 11" x 7" rectangle, about 1 inch thick. Using a sharp knife or pastry wheel, cut the rectangle into 16 triangles. Place the trianges on the prepared baking sheets; cover with plastic wrap and freeze untl the dough is very firm, at least 2 hours or overnight. (At this point, you can freeze the unbaked scones in a resealable plastic bag until ready to bake, up to 3 weeks.)
Preheat the oven to 375°. In a small bowl, lightly beat the egg yolk with the remaining 1/4 cup cream; brush over the tops of the scones and sprinkle generously with sanding sugar, if using. Bake, rotating sheets halfway through, until the tops are golden and flecked with brown spots, 30 to 35 mintues. You can also lift one scone with a spatula to check that the bottom is golden. Transfer to a wire rack to cool Serve warm or at room temperature. They are best eaten the day they are baked.
Lemon-Ginger Scones Variation: Follow instructions for Currant Scones, folding in 3/4 cup (about 4 ounces) diced crystallized ginger and the finely grated zest of 2 lemons after cutting in the butter; omit the currants. Pour 2 1/4 cups heavy cream (instead of 2 cups) into the flour mixture, along with 1/2 cup freshly squeezed lemon juice. Proceed with the recipe.
From Martha Stewart's Baking Handbook by Martha Stewart, copyright © 2005 by Martha Stewart Living Omnimedia Inc., 11 West 42nd Street, New York, NY 10036. All rights reserved. Photographs copyright © 2005 by Jonathan Lovekin. Used by permission of Random House, Inc. For online information about other Random House, Inc. books and authors see RandomHouse.com.