Step 1: Make the Cookie Dough

1. In a large bowl, cream together the butter and sugar until light and fluffy.
2. Mix in the egg and vanilla extract until smooth.
3. In a separate bowl, whisk together the flour, baking powder, and salt.
4. Gradually add the dry ingredients to the wet ingredients, mixing until a dough forms.

Step 2: Color the Dough

1. Divide the dough into sections based on how many colors you want.
2. Add a few drops of gel food coloring to each section and knead until fully incorporated.
3. Adjust the color intensity as needed by adding more food coloring.

Step 3: Chill and Shape

1. Wrap each colored dough ball in plastic wrap and refrigerate for at least 30 minutes.
2. Roll out the dough and cut into shapes or roll into balls for drop cookies.

Step 4: Bake to Perfection

1. Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.
2. Place cookies on the sheet and bake for 8-10 minutes, or until edges are set.
3. Let them cool on a wire rack before serving.