Preheat your oven to 350°F (175°C).

In a large skillet over medium heat, brown the ground beef until fully cooked, about 5-7 minutes. Drain any excess fat.

Add the water, cream of chicken soup, Rotel tomatoes, and sour cream to the skillet. Stir until well combined and heated through, about 3 minutes.

Remove the skillet from heat and fold in 1 cup of shredded cheddar cheese until melted and creamy.

In a large casserole dish, layer half of the crushed Doritos evenly on the bottom.

Pour half of the beef mixture over the Doritos, followed by half of the remaining cheddar cheese.

Repeat the layers with the remaining Doritos, beef mixture, and cheese.

If desired, sprinkle chopped green onions on top for added flavor.

Cover the casserole dish with foil and bake in the preheated oven for 20 minutes.

Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and slightly golden.