In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

In a large bowl, using an electric mixer, cream together the softened butter and granulated sugar until light and fluffy, about 2-3 minutes.

Beat in the egg and vanilla extract until well combined, scraping down the sides of the bowl as needed.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix.

Divide the dough in half, flatten each half into a disc, wrap tightly in plastic wrap, and chill in the refrigerator for at least 30 minutes. This step is crucial for easy rolling and prevents spreading.

Preheat your oven to 375°F (190°C). Line baking sheets with parchment paper.

On a lightly floured surface, roll out one disc of chilled dough to about 0.25 inch (6mm) thickness. Use your favorite holiday cookie cutters to cut out desired shapes.

Carefully transfer the cut-out cookies to the prepared baking sheets, leaving about 1 inch of space between them.

Bake for 8-10 minutes, or until the edges are lightly golden. Baking time may vary depending on the size and thickness of your cookies.

Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely. Cookies must be completely cool before frosting.

For the optional icing: In a small bowl, whisk together the powdered sugar and milk until smooth. Add food coloring if desired for festive colors. Frost the completely cooled cookies and immediately decorate with holiday sprinkles before the icing sets.