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

Cream together the softened unsalted butter and granulated sugar until light and fluffy, about 3-5 minutes.

Add a large egg to the mixture and beat until fully incorporated.

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

Gradually add the dry ingredients to the wet mixture, stirring until a dough forms.

Divide the dough into 3-4 parts and mix in your choice of Jello gelatin powder.

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

Once chilled, roll the dough into balls and roll each in additional sugar.

Place cookies on prepared baking sheets and gently flatten each ball.

Bake for 8-10 minutes, until edges are set and tops are slightly crackled.

Let cookies cool on the baking sheet for 2 minutes before transferring to a wire rack.