Thoroughly wash the grapes under cold running water and pat them dry with a clean kitchen towel. Ensure they are completely dry to help the coating stick.
In a mixing bowl, combine the granulated sugar and Kool-Aid powder. Mix well until the two ingredients are fully integrated.
Place the dry grapes in the bowl with the sugar-Kool-Aid mixture. Gently toss the grapes until they are evenly coated with the mixture. Make sure to cover them thoroughly for maximum flavor.
Once coated, transfer the grapes to a baking sheet lined with parchment paper. Spread them out in a single layer to prevent sticking.
Place the baking sheet in the freezer for about 1-2 hours, or until the grapes are frozen solid. This step enhances the texture and makes them incredibly refreshing.
After freezing, remove the grapes from the freezer and allow them to sit for a few minutes. This will make it easier to eat, as the coating may be slightly hard.