ed (I used a good two or three cups)Other cooked leftovers, if you have them and want to extend the casserolePaprika (for color, optional, I used the smoky Spanish paprika called piment??n, which is quite delicious)Preheat oven to 350F.SAUCE: In a large saucepan, melt the butter til shimmery on MEDIUM. Add the onion, garlic, mushrooms and other veggies and saut?? a bit.