Black Bean and Pineapple Enchiladas

I made Ashley's recipe for enchiladas, and they turned out really good!  I can't recall ever having a good vegetarian enchilada.  Usually they are just cheese or cheese + one vegetable, and you feel gross eating so much cheese.  But I liked that Ashley's recipe uses a minimal amount of cheese (and none inside the enchiladas).

My only changes to the recipe were to use more cilantro, and only half the can of salsa (it was medium and I didn't want them to end up too spicy).

The only problem was that the bottoms of the enchiladas got very tough and stuck to the pan (I should have sprayed it).  Is there a way to remedy this?  I have never made enchiladas before.  Should I pour enchilada sauce on the bottom of the pan?

I will soon use the leftover pineapple to make a favorite dish, "Tropical Breakfast Risotto," and will post the recipe afterwards.