Cream the butter and sugar: In a large bowl, beat softened butter and granulated sugar on medium speed for 2–3 minutes until light and fluffy. Scrape the bowl to make sure everything mixes evenly.

Add egg and extracts: Mix in the egg, vanilla, and almond extract until smooth. Don’t overbeat—just combine.

Combine dry ingredients: In a separate bowl, whisk flour, cornstarch, baking powder, and salt.

Bring the dough together: Add dry ingredients to the wet mixture in two additions. Mix on low until a soft dough forms. If it looks crumbly, add 1–2 teaspoons of milk until it holds together.

Chill: Divide dough into two discs, wrap, and chill for at least 1 hour (or up to 2 days). This step prevents spreading and makes rolling easier.

Preheat and prep: Heat the oven to 350°F (175°C). Line baking sheets with parchment paper.

Roll and cut: On a lightly floured surface, roll one disc at a time to about 1/4 inch thickness. Cut into shapes with cookie cutters. Re-roll scraps once if needed.

Bake: Place cookies on the prepared sheets about 1 inch apart. Bake 8–10 minutes, until edges look set and the bottoms are just turning light golden. The tops should stay pale.

Cool completely: Let cookies rest on the sheet for 2 minutes, then transfer to a rack to cool before icing.

Make the icing: Whisk powdered sugar, milk, corn syrup, and extract until smooth and glossy. Adjust with a few drops of milk to thin, or more sugar to thicken. Tint with gel colors if you like.

Decorate: Dip cookies, flood with a spoon, or pipe borders and fill. Add sprinkles while the icing is wet. Let set 4–6 hours at room temperature before stacking.