Prepare the Dough:

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

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

Gradually incorporate the all-purpose flour, mixing until a soft dough forms.

Divide and Color:

Divide the dough into equal portions, depending on how many colors you wish to use.

Add a different natural food coloring to each portion, kneading until the color is evenly distributed.

Form the Cookies:

Take small pieces of each colored dough and press them together to form a multi-colored ball.

Roll the ball gently to create a smooth, marbled effect.

Place the dough balls onto a baking sheet lined with parchment paper.

Bake:

Preheat your oven to 350°F (175°C).

Bake the cookies for 10-12 minutes, or until the edges are lightly golden.

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