01 - In a medium mixing bowl, thoroughly whisk together the all-purpose flour, baking powder, and salt. Set this mixture aside for later use.
02 - Using an electric mixer in a large bowl, beat the room temperature unsalted butter and granulated sugar together until the mixture is light, fluffy, and pale in color, approximately 2 to 3 minutes.
03 - Add the large egg and pure vanilla extract to the creamed butter and sugar. Continue to beat with the electric mixer until all ingredients are fully combined.
04 - Gradually add the reserved dry ingredients to the wet mixture, mixing on low speed until a soft, cohesive dough forms.
05 - Divide the prepared cookie dough into two equal halves. Gently flatten each half into a disc shape, wrap them tightly in plastic wrap, and refrigerate for a minimum of 1 hour. This chilling process helps to firm the dough and prevents spreading during baking.
06 - Preheat your oven to 350°F. Line several baking sheets with parchment paper to prevent sticking and ensure even baking.
07 - On a lightly floured surface, roll out one disc of chilled dough to an even 1/4-inch thickness. Using a heart-shaped cookie cutter, cut out shapes from the dough. Reroll any scraps and cut additional cookies as needed.
08 - Carefully place the cut-out cookies onto the prepared baking sheets, ensuring they are spaced approximately 1 inch apart to allow for proper airflow.
09 - Bake the cookies for 8 to 10 minutes, or until the edges appear lightly golden. Remove from the oven and let them cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
10 - In a medium bowl, whisk together the sifted powdered sugar, milk, light corn syrup, and pure vanilla extract until the icing is smooth and free of lumps. Adjust the consistency by adding a small amount of additional milk if the icing is too thick.
11 - Divide the prepared icing into separate bowls and add food coloring as desired, stirring well to achieve your preferred shades.
12 - Once the cookies have cooled completely, decorate them with the tinted icing. You can use a piping bag, a squeeze bottle, or simply a spoon to apply the icing. Allow the icing to fully set before serving or packaging the cookies.