01 - Whisk together flour, baking powder, and salt in a medium bowl until evenly combined.
02 - Beat softened butter and granulated sugar in a large bowl until light and fluffy, approximately 2–3 minutes.
03 - Mix in egg, vanilla extract, and almond extract if using, until fully incorporated into the butter mixture.
04 - Gradually add dry ingredients to wet ingredients, mixing on low speed just until dough forms and no dry streaks remain.
05 - Divide dough in half, shape each portion into a flat disk, wrap tightly in plastic wrap, and refrigerate for at least 1 hour.
06 - Preheat oven to 350°F and line baking sheets with parchment paper.
07 - On a lightly floured surface, roll dough to ¼-inch thickness and cut shapes using shamrock or round cookie cutters.
08 - Place cut cookies on prepared baking sheets, leaving 1 inch of space between each cookie.
09 - Bake for 8–10 minutes until edges are just beginning to turn golden. Let cool on sheet for 2 minutes, then transfer to wire rack.
10 - Whisk powdered sugar, milk, and vanilla extract until smooth. Add green food coloring gradually until desired shade is achieved.
11 - Spread or pipe icing onto completely cooled cookies and add sprinkles while icing is still wet. Allow icing to set before serving.