Preheat your oven to 400°F (200°C). Line two baking sheets with parchment paper. Toss cauliflower and sweet potatoes with olive oil, ground cumin, salt, and pepper on one sheet. On another sheet, combine red bell peppers and onions with the same seasoning. Roast for 30–35 minutes.

Once veggies are roasted, reduce oven temperature to 350°F (175°C). Grease a 9-inch square baking dish with olive oil. Mix chopped cilantro into the red salsa.

Spread ½ cup of salsa in the baking dish. Layer with corn tortillas, half of the black beans, a third of the roasted veggies, half of the spinach, and a third of the cheese. Repeat this process to create another layer.

Cover the dish loosely with aluminum foil and bake for 20 minutes. Remove the foil and bake uncovered for an additional 10 minutes. Look for bubbly, golden cheese.

Let the casserole cool for about 10 minutes before serving to help the layers set. Enjoy the aroma while you wait!