Banana Muffins with chopped chocolate and nutella make for a great combination.
Regarding flours, you can use either all-purpose flour or spelt flour, but I mixed them.
I like to use oil in my quickbreads and snack cakes. You can use melted butter in this recipe.
You can swirl more Nutella through the muffins if desired, or if you prefer, serve muffins with option of topping with more Nutella. I find these best served warm.