Make the dough: In a bowl, whisk flour, baking powder, and salt. In a separate large bowl, beat butter and sugar until light and creamy, about 2–3 minutes. Mix in egg, vanilla, and almond extract if using.

Combine: Add dry ingredients to wet in two additions, mixing just until a soft dough forms. If crumbly, knead gently by hand until it comes together.

Chill: Divide dough into two discs, wrap, and chill for 1 hour. This helps keep shapes sharp.

Roll and cut: Preheat oven to 350°F (175°C). Roll dough on a lightly floured surface to about 1/4-inch thickness. Cut with Christmas-themed cutters (trees, stars, snowflakes, stockings).

Bake: Place on a lined baking sheet and bake 9–12 minutes, until edges are set and just starting to turn golden. Cool completely on a rack.

Make royal icing: In a mixing bowl, whisk powdered sugar and meringue powder. Add 5–6 tablespoons water and extract. Beat on medium speed for 2–3 minutes until thick and glossy with soft peaks. Add more water a teaspoon at a time to reach piping consistency (toothpaste-thick).

Create flood icing: Transfer half the icing to separate bowls for colors. Thin with water, a few drops at a time, until it reaches flood consistency. It should smooth out in 10–15 seconds when you run a line through it.

Color: Add gel colors a little at a time. Stir gently to avoid bubbles.

Outline and flood: Use piping icing to outline each cookie shape. Let set 2–3 minutes. Fill with flood icing, using a toothpick to nudge icing into corners and pop air bubbles.

Dry time: Let cookies dry uncovered at room temperature. Surface dries in 1–2 hours; full set takes 6–8 hours or overnight.

Add details: Once the base is set, pipe details like snowflake lines, dots, garlands, and lettering with piping icing. Add sprinkles while icing is wet so they stick.