Beat the softened butter and granulated sugar together for 2–3 minutes, until light and creamy. Add the egg and vanilla extract, then beat until evenly combined.

Whisk the flour, baking powder, and salt in a separate bowl. Add the dry ingredients gradually to the butter mixture, mixing just until a soft dough forms.

Tint the dough with black gel food coloring, adding it gradually until the desired deep color is reached. Divide the dough into two portions, flatten each into a disk, wrap, and chill for about 30 minutes.

Roll one dough disk on a lightly floured surface to about ¼ inch (6 mm) thick. Cut cat shapes with a cat-shaped cookie cutter and transfer them to parchment-lined baking sheets.

If the cut shapes become soft, chill them for 10–15 minutes before baking. Bake at 350°F (175°C) for 8–10 minutes, until the edges are set.

Cool the cookies on the baking sheet for 5 minutes, then transfer them to a wire rack. Once completely cool, add candy eyes or pipe white icing eyes, whiskers, and mouths, plus yellow details for classic cat eyes.