01 - Whisk together flour, baking powder, and salt in a medium bowl until evenly blended.
02 - Beat softened butter and granulated sugar in a large bowl until light and fluffy, approximately 2–3 minutes.
03 - Add egg, vanilla extract, and almond extract if using. Mix until fully incorporated into the butter mixture.
04 - Gradually add dry ingredients to wet ingredients, mixing on low speed just until dough forms. Avoid overmixing.
05 - Divide dough in half and shape each portion into a disk. Wrap tightly in plastic wrap and refrigerate for at least 1 hour.
06 - Preheat oven to 350°F. Line baking sheets with parchment paper.
07 - On a lightly floured surface, roll dough to ¼-inch thickness. Cut shapes using shamrock or round cookie cutters.
08 - Arrange cookies 1 inch apart on prepared baking sheets. Bake for 8–10 minutes until edges are just turning golden.
09 - Let cookies rest on baking sheet for 2 minutes, then transfer to wire rack to cool completely before icing.
10 - Whisk powdered sugar, milk, and vanilla extract until smooth. Add green food coloring gradually to achieve desired shade.
11 - Ice cooled cookies and immediately apply sprinkles while icing is wet. Allow icing to set completely before serving.