1. Grease a 9×13-inch baking dish with butter or cooking spray. Cut the tortillas into strips or wedges and arrange a layer over the bottom of the dish, slightly overlapping so there are no big gaps.

2. In a large skillet, heat the olive oil over medium heat. Add the diced onion and red bell pepper and sauté until softened and lightly golden.

3. Stir in the black beans, corn, and drained diced tomatoes with green chiles. Cook for a few minutes until warmed through and any excess moisture begins to evaporate, then remove from heat.

4. In a large mixing bowl, whisk together the eggs, milk, and sour cream until smooth. Season with kosher salt, black pepper, chili powder, cumin, smoked paprika, garlic powder, and onion powder.

5. Spoon half of the veggie mixture evenly over the tortilla layer in the baking dish. Sprinkle with about half of the cheddar and pepper jack cheese.

6. Add another layer of tortillas over the cheese, then top with the remaining veggie mixture and most of the remaining cheese, reserving a small handful for the top.

7. Slowly pour the egg mixture evenly over the layered tortillas, veggies, and cheese, tilting the pan slightly if needed to help it flow into the corners and layers. Sprinkle the reserved cheese over the top.

8. Cover the dish tightly with foil and bake at 350°F (175°C) for 25–30 minutes, until the eggs are mostly set. Remove the foil and bake for another 10–15 minutes, until the top is golden, the cheese is bubbly, and the center is just set with a slight jiggle.

9. Let the casserole rest for about 10 minutes, then sprinkle with sliced green onions and chopped cilantro. Slice into squares and serve warm, with avocado, salsa, jalapeños, or hot sauce on the side if desired.