We recently had that same problem. The kids wanted cupcakes and I wanted to make a new kind instead of the same old ones they already love . So I began thinking watermelon cupcakes.
First we need to make a watermelon purée . I did 2 cups of cut up watermelon and a tsp of fresh lemon juice. I puréed it in the blender
Ingredients
1 1/2 cups of gluten free flour ( all pour purpose same ratio for non gluten free)
2 tsp baking powder
1 tsp xanthan gum
1/2 cup butter we used almond butter for dairy free
1 cup sugar
1 tsp lemon zest
2/3 cup of your water Mellon purée
Creme your butter and sugar and slowly add your dryly ingredients, purée and lemon zest
Bake at 350 for around 20 mins
We used a typical butter creme frosting
1/2 cup butter
1/2 cup crisco
5 cups powdered sugar
1/4 cup of water Mellon purée