makes about 6 cups of sauce, enough for two 8x13" pans of enchiladas (about 12 enchiladas each)
Preheat oven to 400°F. Toss the butternut squash (or sweet potatoes) with a tablespoon of olive oil and roast on a parchment paper lined sheet pan until tender, but not fully cooked, about 20 minutes.
Blend tomatoes with the salsa, chipotle adobo, water, and apple cider vinegar in a blender of food processor and set aside.
Melt butter in a saucepan over medium-high heat until sizzling. Sprinkle in the corn flour (or regular flour) and cook a couple minutes, stirring with a wooden spoon. Pour in the tomato purée, bring to boil, lower heat, and let simmer, partially covered, while you assemble the filling.
Combine the roasted butternut squash or sweet potatoes, hominy, black beans in a bowl and gently mix in the sour cream.
Butter two rectangular baking dishes, each about 8x13". Put a couple big spoons of sauce in the bottom of each dish. Set up an assembly line of tortillas, filling, and cheese, saving some cheese for the top. Roll up the tortillas and place snuggly into baking dishes. (If you have extra filling, make more enchiladas or set filling aside to bake on its own with cheese on top.) Pour the remaining sauce over the top of the enchiladas, dividing equally between the two pans, then sprinkle with cheese. Spray the inside of a piece of foil with non-stick spray and then cover the enchiladas tightly.
Bake at 400°F until hot, about 30–40 minutes, removing the foil for the last 10 minutes to bubble and crisp the cheese. (Thaw in refrigerator first if you are baking from frozen.)