01 -
Beat softened unsalted butter and granulated sugar together in a large bowl until light and fluffy, approximately 2 to 3 minutes.
02 -
Incorporate the egg yolk and vanilla extract, mixing until fully combined and smooth.
03 -
Gradually add the all-purpose flour and salt, mixing just until incorporated to avoid overworking the dough.
04 -
Form the dough into 1-inch diameter balls and arrange on a parchment-lined baking sheet, spaced 2 inches apart. Refrigerate for 30 minutes to maintain shape during baking.
05 -
Preheat oven to 350°F (175°C). Using your thumb or the back of a rounded teaspoon, gently press an indentation into the center of each dough ball.
06 -
Bake for 12 to 14 minutes, or until the edges are just beginning to turn golden. Remove from oven and cool on the baking sheet for 5 minutes.
07 -
Transfer cookies to a wire rack and cool fully before applying frosting.
08 -
Beat powdered sugar, whole milk, softened butter, and vanilla extract until creamy and smooth. Gradually add green gel food coloring until a vivid green shade is achieved.
09 -
Spoon or pipe green frosting into each cookie indentation and gently press a red heart sprinkle into the center while frosting is still wet.