In a medium mixing bowl, whisk together the all-purpose flour, baking powder, and salt until evenly combined. Set aside.

In a large bowl, beat the softened butter and granulated sugar with an electric mixer for 2–3 minutes until light and fluffy. Add the egg, vanilla extract, and almond extract, if using. Mix until smooth.

Gradually add the dry ingredients to the butter mixture, mixing on low speed until a soft dough forms. Divide the dough into two portions, flatten into disks, and wrap in plastic. Refrigerate for at least 1 hour to help the cookies hold their shape.

Preheat the oven to 350°F and line two baking sheets with parchment paper. Roll the chilled dough on a lightly floured surface to about ¼-inch thickness. Cut out ghost shapes using a cookie cutter and arrange them about 1 inch apart on the prepared baking sheets. Chill the cutouts in the freezer for 10 minutes.

Bake for 9–11 minutes, or until the cookies are set and the edges are just beginning to turn lightly golden. Let them cool on the baking sheets for 5 minutes before transferring them to a wire rack to cool completely.

In a medium bowl, whisk together the powdered sugar, 2 tablespoons of milk, corn syrup, and vanilla extract until smooth. Add more milk, a few drops at a time, if needed. Reserve some thicker icing to outline the cookies, then thin the remaining icing slightly to fill the centers. Pipe a white outline around each cooled cookie, fill the centers, and use a toothpick to smooth the icing. Let the surface set for about 15–20 minutes.

Melt the chocolate chips in a microwave-safe bowl in 15-second intervals, stirring until smooth. Transfer the chocolate to a small piping bag and create two eyes and an oval-shaped mouth on each ghost. Allow the icing and chocolate to set completely before serving or stacking.