In a large mixing bowl, cream together softened butter and granulated sugar until light and fluffy.

Add the egg and vanilla extract, mixing until well combined.

In a separate bowl, whisk together flour, baking powder, and salt.

Gradually add the dry ingredients to the butter mixture, mixing until the dough comes together.

Divide the dough into three equal portions. Use food coloring to tint one portion yellow, one portion orange, and one portion red. Wrap each colored dough in plastic wrap and refrigerate for at least 1 hour.

Preheat the oven to 350°F (175°C). On a lightly floured surface, roll out each portion of dough to about 1/4-inch thickness. Use a leaf-shaped cookie cutter to cut out cookies from each color of dough.

Place the cookies on a baking sheet lined with parchment paper, spacing them about 1 inch apart. Bake for 8-10 minutes, or until the edges are lightly golden.

Remove from the oven and let cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.