Preheat oven to 350 degrees F. Line a baking sheet with parchment paper or a silicone mat (optional).
In a large mixing bowl, beat softened butter and sugar together until fluffy. Add dry jello and mix until incorporated. Add eggs and beat again.
Add flour, baking powder, and salt. Beat well until cookie dough is just combined. Be sure to scrape the sides as needed.
Using a cookie scoop, scoop dough onto your prepared baking sheet. Roll each ball of dough until it is smooth. Spray the bottom of a glass with cooking spray and gently flatten each ball of dough.
Bake for 9-10 minutes or until edges begin to brown.
Frosting
Beat powdered sugar, butter, and milk together. If it's too thick, add a little milk. If it's too thin, add a bit more powdered sugar.
When cookies are cool, frost, add sprinkles, and enjoy!
Notes
Store cookies in an airtight container at room temperature for up to 5 days. They will remain soft for at least 3 days.
Freeze unfrosted cookies in an airtight containers or freezer bags for up to 6 months.
These cookies can be made with just about any flavor of jello. Try making them rainbow colors by diving the dough into small bowls and using a few different flavors of jello.