In a large bowl, gently fold together the sweetened condensed milk and whipped topping until fully combined and smooth.

Pour in the Kool-Aid powder and continue folding until completely dissolved and the filling is a vivid, uniform color throughout.

Transfer the filling to the graham cracker pie crust and use a spatula to smooth it into an even layer.

Cover the pie with plastic wrap or foil and refrigerate for at least 2 hours until completely set.

Once set, slice and serve the pie chilled or frozen, dolloping each slice with whipped cream if desired.