Preheat oven to 350°F and line baking sheets with parchment paper.
In a stand mixer, cream butter and sugar for 2–3 minutes until light and fluffy.
Beat in egg, vanilla extract, peppermint extract (if using), and green food coloring until evenly combined.
Add baking powder and salt, mixing briefly to combine.
Gradually add flour until the dough comes together.
Divide dough in half and shape into discs; wrap in plastic and chill for 1–2 hours.
Roll each disc to 1/4-inch thickness between sheets of parchment; cut into shapes and transfer to baking sheets, chilling for 10 minutes.
Bake for 8–10 minutes, until edges are just turning golden. Allow cookies to rest on the baking sheet for 2 minutes, then transfer to wire racks to cool completely.
Royal Icing
Whisk powdered sugar, meringue powder, and warm water until smooth.
Stir in vanilla extract and green gel food coloring until desired shade is reached.
Transfer icing to piping bags, outline and flood cookies, and allow to set fully before storing.
Notes
Store iced cookies in an airtight container at room temperature for up to 5 days.Chilling the dough discs overnight develops deeper vanilla notes and ensures sturdier shapes.Use gel food coloring drop by drop to achieve a vibrant hue without altering dough consistency.
Keyword Green Sugar Cookies, Grinch Sugar Cookies, Holiday Cookies, Royal Icing