Whisk the dry ingredients. In a medium bowl, whisk the flour, cornstarch, baking powder, and salt. Set aside.

Cream the butter and sugars. In a large bowl, beat the softened butter, granulated sugar, and powdered sugar until light and fluffy, about 2–3 minutes. Scrape the bowl as needed for even mixing.

Add eggs and flavorings. Beat in the egg and egg yolk until smooth. Mix in the vanilla and almond extract. The mixture should look creamy and cohesive.

Combine wet and dry. Add the dry ingredients in two additions, mixing on low until just combined. If the dough seems crumbly, add 1 tablespoon of milk or cream. The dough should be soft but not sticky.

Divide and chill. Split the dough into two equal portions. Flatten each into a disc, wrap tightly in plastic, and chill for at least 1 hour (or up to 2 days). Chilling helps the dough relax and keeps cookies from spreading.

Preheat and prep. When ready to bake, preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.

Roll the dough. Work with one disc at a time. Place it between two sheets of parchment and roll to 1/4 inch (6 mm) thickness for soft cookies that still hold their shape. For slightly firmer cookies, roll to 3/16 inch.

Cut shapes. Use floured cookie cutters to cut shapes, transferring them to the prepared baking sheets. Gather scraps, reroll once or twice as needed. For ultra-clean edges, pop the cut shapes into the fridge for 10 minutes before baking.

Bake. Bake for 8–10 minutes, depending on size. The edges should look set but not browned. Pull them while they still look pale for a soft texture.

Cool completely. Let cookies rest on the sheet for 5 minutes, then transfer to a wire rack to cool fully before decorating.

Decorate. Use royal icing for clean lines and detailed designs, or a simple powdered sugar glaze for an easy, glossy finish. Let icing dry completely before stacking or storing.