8 ounces unsalted butter (2 sticks; 225g); firm but pliable, about 60°F (16°C)
10 ounces sugar (1 1/2 cups; 280g)
2 1/2 teaspoons baking powder (10g)
1 1/4 teaspoons Diamond Crystal kosher salt (7g) (For table salt, use half as much by volume or use the same weight)
Pinch of freshly grated nutmeg
1 large egg, cold
1 tablespoon pure vanilla extract (15mL)
11 1/4 ounces all purpose flour (2 1/4 cups; 320g)
Assorted sanding sugars, nonpareils, and sprinkles, or plain granulated sugar blended with vanilla seeds, luster dust, or powdered food coloring for finishing