Preheat the oven to 350°F (175°C) and grease a 9 x 13-inch baking dish.

Brown the lean ground beef in a skillet over medium heat, breaking it into small crumbles as it cooks. Drain any excess fat.

Stir the taco seasoning into the cooked beef according to the packet directions, adding the small amount of water called for on the package. Simmer briefly until the beef is well coated.

In a separate bowl, stir together the condensed cream of chicken soup, sour cream, and undrained Rotel until the mixture is combined.

Lightly crush the Doritos into bite-size pieces rather than fine crumbs. Reserve a small handful if you want a crunchy topping after baking.

Spread a layer of crushed Doritos across the greased baking dish. Add half of the seasoned beef, half of the soup mixture, and some shredded cheese.

Repeat the Doritos, beef, soup mixture, and cheese layers. Finish with the remaining cheese spread evenly across the top.

Bake the casserole uncovered for about 30 minutes, until hot and bubbling and the cheese is fully melted. Let it rest for 5 minutes, then add reserved Doritos or your favorite toppings before serving.