4C AP flour
1T baking powder (make sure it's fresh!)
1t kosher salt
1/2t cream of tartar
zest of a large lemon (save the juice for the glaze)
1 stick + 5T unsalted cold butter, cut into small cubes
1C + 6T half & half
1 large egg
powdered sugar & lemon juice for the glaze
Preheat the oven to 375'
Using a food processor fitted with a metal blade (or a pastry cutter in a bowl), cut the butter into the dry ingredients until you see some pea-sized pieces, and some course-meal-looking pieces of butter in the flour. These uneven pieces of butter will give you the tender layers you want in a scone or biscuit. DO NOT OVERMIX.
Whisk the egg into the half & half, then mix into the flour, just until a ball forms. I do this by hand. Then turn the dough out onto a lightly floured work surface, and gently knead the dough for just a few turns until all the dry bits are incorporated. Roll the dough into a rectangle about 1" thick. Using a pizza cutter or thin, sharp knife or bench scraper, cut the dough into squares, then cut the squares in half to make triangles. Clean, sharp cuts will help the sides of the scones puff up while baking.
Space the scones out a bit on baking sheets lined with parchment, and bake about 20-25 minutes, until the tops just begin to turn golden.
Allow to cool for about 10 minutes, then glaze. If you glaze when the scones are too hot, the glaze will melt right off, like that guy's face in Raiders of the Lost Ark. If you wait til they're too cool, the glaze won't dry properly. 10 minutes is perfect.
Sift about 1.5C of powdered sugar into a glass or ceramic bowl. Do not use metal, or it will react with the lemon juice, and the glaze will taste like metal. Squeeze a little lemon juice over, and stir (again, with something NOT METAL). Add lemon juice until you get a thick but still sort of runny glaze. It should coat the back of a spoon, but still drip...slowly.
*Note: If you decide to make the full batch and freeze half of them for later, freeze the scones on a sheet pan, then transfer them to a freezer-safe bag or container for up to 1 month. Bake from frozen. They might just take a bit longer to bake.