Steps

1. Whisk the flour, baking powder and salt in a bowl.
2. Beat the butter and sugar on medium speed until creamy and light, then beat in the egg, vanilla and almond extract.
3. Mix in the flour on low just until a soft dough forms. Divide it in half.
4. Roll each half between two sheets of parchment to an even 1/4 inch thick. Stack the sheets on a sheet pan and refrigerate until firm.
5. Heat the oven to 350°F (175°C) and line sheet pans with parchment.
6. Peel off the top parchment and cut shapes with cookie cutters, dipping them in flour between cuts. Move the cookies to the lined pans 1 inch apart. Re-roll and chill scraps.
7. Chill the cut cookies on the pan for 10 minutes. Cold dough keeps sharp edges in the oven.
8. Bake until the edges are just barely turning golden and the centers look set. Smaller shapes bake faster.
9. Cool 5 minutes on the pan, then move to a rack and cool completely before icing.
10. For the icing, beat the powdered sugar, meringue powder, vanilla and 6 tablespoons water on medium-low until glossy and stiff peaks form. This is outline icing.
11. Tint portions with gel coloring. To make flood icing for filling in, stir in water a few drops at a time until a ribbon drizzled on top disappears in about 10 seconds. Keep all icing covered with a damp towel, since it dries fast.
12. Pipe outlines with the thicker icing, then fill in with flood icing and nudge it into corners with a toothpick. Add sprinkles while wet.
13. Let the iced cookies dry at room temperature, uncovered, until the icing is hard.