The recipe comes from the KAF All Purpose Baking Cookbook. If you prep the ingredients in advance - grate the cheese and chop the scallions - they come together really fast. I nearly always stir together the dough, shape and cut them, and flash freeze them. Then you can easily pull one or two out and bake them as needed. Once baked, they're best the first day. After that, a minute or two in the oven part of the toaster does wonders to refresh them and re-crisp the outer edges.
2 cups (8 1/2 ounces) flour or 8 ounces pastry flour (I just use all-purpose)
1/2 teaspoon salt
1 tablespoon sugar
1 tablespoon baking powder
6 tablespoons (3 ounces, 3/4 stick) cold butter, cut into pieces
2 large eggs, beaten
1/3 cup (2 3/4 ounces) cream or sour cream (I have always used cream)
1 tablespoon Dijon mustard
1 cup (4 ounces) grated sharp cheddar cheese
3-5 scallions (1 cup, 2 ounces), chopped
If you're baking the scones now, preheat the oven to 375F. Grate the cheddar and chop the scallions; set aside.
In a large bowl, whisk together the flour, salt, sugar, and baking powder. Rub in the butter with your fingers. (It's kinda fun, actually! You can have some lumps of butter about the size of a pea remaining.)
In a small container (I just use a liquid measuring cup), whisk together eggs, cream, and mustard. Add this to the dry ingredients, and stir just until it comes together. Stir in the cheese and scallions. Mix until just combined. It'll be the consistency of cookie dough.
Liberally flour the counter (or a cutting board, or a baking mat - whatever) and your hands. Pat the dough into a 6x9" rectangle, about 1 inch thick. Cut the dough into six rectangles, and then cut each into two triangles, for a total of 12 triangles.
If you're baking them now, place them on a cookie sheet lined with parchment or a silpat (or you can use an unlined, greased sheet). Bake for 18-20 minutes or until puffed and golden brown. If you're not baking them now, place the scones on a cookie sheet lined with parchment and freeze them until solid (say, 30-60 minutes, or until you remember to check the freezer). The frozen scones can be stored in a ziploc bag. I'd imagine they will last at least several weeks, frozen. You can bake them directly from the freezer without an increase in baking time.
Note: if you double the recipe - advisable, since it only makes a dozen - it's much easier to shape the scones in two batches. Divide the dough in half and make each half into a 6x9" rectangle, then follow the directions above.