Preheat the oven to 400°F then place the diced butternut squash, sliced onion, jalapeno and poblano pepper in a 9 x 13” baking dish and toss with high heat oil. Sprinkle with cumin, salt & pepper (to taste) then mix until evenly distributed. Roast vegetables in the oven for about 40 to 45 minutes, until the squash is tender. Remove from oven then lower temperature to 350°F.Transfer the roasted vegetables to a large bowl along with 1 cup salsa, drained and rinsed black beans and chopped cilantro. Using the same baking dish that you roasted the veggies in, prepare the casserole by spreading a thin layer of the salsa along the bottom, then cover with a layer of tortillas. Top the tortillas with 1/3 of the roasted vegetable mixture then 1/2 cup cheese.Layer tortillas on top of the vegetables followed by the 1 cup of baby spinach leaves. Top with a thin layer of the salsa and another 1/3 of the roasted vegetables then 1/2 cup shredded cheese.Lastly, add the last of the tortillas, a thin layer of salsa and the last 1/3 of the vegetables on top. Sprinkle with remaining cheese and bake in the oven for 20 minutes, until light golden brown on top.Allow it to cool for at least five to ten minutes then cut into squares and serve. Garnish with avocado, cilantro or plain yogurt.