Preheat your oven to 350°F (175°C) and line your baking sheets with parchment paper.

In a large mixing bowl, cream together the softened unsalted butter and granulated sugar using an electric mixer until light and fluffy, about 3 to 5 minutes.

Add a large egg and beat until fully incorporated, achieving a smooth consistency.

In a separate bowl, whisk together the all-purpose flour, baking powder, and salt.

Gradually add the dry ingredients to the wet mixture, folding until a soft dough forms. Avoid overmixing.

Divide the dough into 3 to 4 equal portions and mix in 1 to 2 tablespoons of different Jello powder flavors into each portion.

Wrap each portion of the colored dough in plastic wrap and chill in the refrigerator for 15 to 20 minutes.

Roll each chilled portion into balls about 1 inch in diameter and coat in additional sugar, slightly flattening them on the baking sheets.

Bake cookies for 8 to 10 minutes until edges are set and tops are crackled. Do not overbake.

Allow cookies to cool on the baking sheets for 2 minutes before transferring to a wire rack to cool completely.