Preheat your oven to 350°F (175°C). Lightly grease a 9x13 inch baking dish.

In a large skillet over medium heat, cook the ground beef and chopped onion until the beef is browned and the onion is soft. Drain any excess fat.

Add the minced garlic and cook for an additional minute until fragrant.

Stir in the taco seasoning, salsa, black beans (if using), and corn. Simmer for about 5 minutes, allowing the flavors to meld together. Remove from heat and let it cool slightly before stirring in the sour cream.

Start with a layer of roughly crushed Doritos at the bottom of the prepared baking dish, saving enough for the top layer.

Spoon half of the beef mixture over the Doritos, then sprinkle with one cup of shredded cheese.

Add another layer of crushed Doritos, followed by the remaining beef mixture.

Top with the remaining shredded cheese.

Bake in the preheated oven for 20-25 minutes, or until the casserole is heated through and the cheese is melted and bubbly.

Garnish with chopped green onions and sliced jalapeños, if desired.

Serve hot, with additional sour cream on the side if you like.