Preheat oven to 375°. Line a rimmed baking sheet with parchment paper.
In a large bowl, whisk together flour, baking powder, nutmeg, and salt. Using a pastry blender or 2 forks, cut butter into flour mixture until it resembles coarse crumbs. Add 1 cup eggnog to flour mixture, stirring with a fork until a shaggy dough begins to form. Working gently, bring mixture together with hands until a dough forms. (If dough won’t come together, add more eggnog, 1 tablespoon at a time, until it does.)
Turn out dough onto a lightly floured surface, and knead gently by patting dough and folding it in half until smooth, 3 to 5 times. Using a rolling pin, roll out dough to a ¾-inch thickness. Using a 2¼-inch round cutter dipped in flour, cut as many scones as possible from dough without twisting cutter, rerolling scraps as needed. Place scones, evenly spaced, on prepared baking sheet. Freeze until firm, approximately 10 minutes.
Brush tops of scones with remaining 1 tablespoon eggnog.
Bake scones until edges are golden brown, 20 to 25 minutes. Serve warm or at room temperature.