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

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

Beat in the egg until fully combined.

In another bowl, whisk flour, baking powder, and salt.

Gradually mix the dry ingredients into the butter mixture until a dough forms.

Divide the dough into 3–4 equal parts and add 1–2 tbsp of a different Jello flavor to each portion. Mix well.

Chill dough portions for 15–20 minutes.

Roll dough into balls, coat with sugar, and slightly flatten.

Bake for 8–10 minutes or until edges are set and tops are crackled.

Cool on the sheet for 2 minutes, then transfer to a wire rack.