When testing this recipe, various flavoring methods for the strawberry-flavored cookie dough were used. Freeze-dried strawberries, Nesquick Strawberry milk powder, and strawberry jam all worked but not as well as Strawberry Jello powder. It gave the dough the color, texture, and most importantly, the FLAVOR needed. That being said, if using a substitution, using freeze dried strawberries blended to a powder would be the best substitution.