Wash and dry all produce. Preheat oven to 350 degrees. Lightly oil an 8-by-8-inch baking dish. Halve, core, and seed green pepper, then cut into small squares. Trim, then thinly slice scallions, separating greens and whites. Halve and core tomato, then cut into small cubes. Drain and rinse beans.

Heat a large drizzle of oil in a medium pot over medium-high heat. Add green pepper and scallion whites. Cook, tossing, until tender, about 5 minutes. Season with Southwest spice, 1/4 tsp chili powder, salt, and pepper. TIP: Add more chipotle for extra heat, but save some for the crema.

Stir 3 TBSP tomato paste into pot (we sent more). Let cook for about 1 minute. Stir in beans and 3/4 cup water. Let simmer until slightly thickened, 2-4 minutes.

Arrange three tortillas in a single layer on the bottom of your oiled baking dish, cutting one tortilla in half to fit. Add all of the bean mixture to dish and spread out evenly. Layer remaining tortillas on top, again cutting one in half to fit. Gently press down on tortillas to remove any air pockets. Scatter cheese over top. Cover dish with aluminum foil. Bake in oven until filling is hot and cheese melts, 20-25 minutes.

Meanwhile, in a small bowl, stir together sour cream, 1 TBSP water, and as much of the remaining chili powder as you like. Season with salt.

Once casserole is done baking, remove from oven and let rest 5 minutes. Cut into four squares and divide between plates. Drizzle crema over top. Garnish with scallion greens and tomatoes serve.