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

Cream together softened unsalted butter and granulated sugar until light and fluffy, about 2-3 minutes.

Add the large egg to the mixture and beat until fully incorporated, about 1 minute.

In a separate bowl, whisk together all-purpose flour, baking powder, and salt. Gradually add this dry mixture to the wet ingredients and fold gently until just combined.

Divide the dough into 3-4 portions and mix in the Jello gelatin powder until color is uniform.

Chill the dough in the refrigerator for 15-20 minutes, covered with plastic wrap.

Roll the dough into small balls, coat each ball in additional sugar, and slightly flatten them on the baking sheets.

Bake the cookies for 8-10 minutes until the edges are set and centers are still soft.

Cool on the baking sheet for 2 minutes before transferring to a wire rack to cool completely.