Butternut Squash Enchilada Casserole

medium sized butternut squash, peeled and diced (approx. 2 and 1/2 lbs)

yellow onion, sliced

poblano or green bell pepper, cored and sliced

jalapenos, cored and sliced

high heat oil (such as sunflower oil)

cumin powder

salt & pepper

black beans, drained and rinsed

cilantro, chopped

fresh baby spinach leaves (optional)

salsa or enchilada sauce

small or 6 large corn tortillas; cut into quarters*

and 1/2 cups shredded Mexican cheese**