Line a baking sheet with parchment paper. Put the flour, sugar, salt, baking powder, and spices in a food processor. Process for 3 seconds. Scatter the diced butter over the flour mixture, and pulse 5-7 times just to break up the butter. Transfer the mixture to a large mixing bowl.
In a separate bowl or 4-cup glass measure, whisk together the eggnog, egg, and vanilla. Pour this eggnog mixture over the flour mixture, and stir until a soft dough comes together.
Scoop the dough onto a lightly-floured surface. Scatter a small amount of flour on top of the dough, and then gently knead it by hand a few times. Form the dough into a ball, and then flatten the ball into a disk. Roll the dough into a circle that is approximately 3/4-inch.
Use a floured, 2-inch-diameter biscuit cutter to cut out rounds. Space the rounds about 1/2 apart on the prepared baking sheet. Put the baking sheet in the freezer for 30 minutes to firm up the butter. Meanwhile, preheat the oven to 425°F.
Brush the frozen scones with eggnog. Bake, from frozen, until the scones puff and turn golden brown -- 18-20 minutes, depending on your oven.