Preheat your oven to 350°F (175°C).
In a large skillet, melt the butter over medium heat. Add the chopped onion and cook until softened and translucent.
Stir in the cream cheese, chicken, soup, tomatoes, black beans, chili powder, and cumin. Cook and stir until the cream cheese is fully melted and all ingredients are well combined.
In a greased 9x13-inch baking dish, spread 1/3 of the crushed Doritos on the bottom.
Pour half of the chicken mixture over the Doritos and spread it evenly.
Sprinkle half of the shredded cheese on top of the chicken mixture.
Add the remaining chicken mixture over the cheese.
Top with the rest of the Doritos and shredded cheese.
Bake for 30 minutes, or until the cheese is bubbly and the edges are golden brown.
Serve and enjoy!