Preheat the oven to 350℉. Line two cookie sheets/baking sheets with parchment paper, baking mat, or spray with cooking spray.
In a large bowl using an electric hand mixer, beat together the butter and sugar until light and fluffy, about 2 minutes.
1 cup (2 sticks) unsalted butter, 1 cup granulated sugar
Add in the eggs and vanilla extract and beat on low speed just until the eggs are incorporated.
2 large eggs, 1 teaspoon vanilla extract
In a separate smaller bowl, whisk together the flour, baking powder, baking soda, and salt until combined.
3 cups all-purpose flour, 1 teaspoon baking powder, ½ teaspoon baking soda, ¼ teaspoon salt
Dump the dry ingredients into the wet ingredient bowl and beat on low speed just until combined and no flour streaks remain in the dough.
Divide the cookie dough into 4 equal portions and put each one in a separate bowl. Add one package of Jello powder to each bowl and mix until the dough is evenly colored.
4 boxes (3 oz each) different flavors Jello
Place the additional granulated sugar (for rolling) into a small bowl.
additional granulated sugar for rolling
Use a medium cookie scoop, about 1½ tablespoons dough, to scoop the dough and roll into balls. Roll each ball in the granulated sugar until well coated, and place 12 cookie dough balls per cookie sheet.
Bake for 9-12 minutes or until the edges are just set and turning very lightly golden brown. * The middle of the cookies should not look wet or like raw dough, but look cooked but still soft and lighter in color. They will continue cooking slightly while cooling on the warm pan so be careful to not overbake them in the oven. Remove the cookies from the oven and let them cool on the cookie sheet for about 15 minutes before removing them to a cooling rack to cool completely.