Preheat the oven to 350 degrees F. Spoon a couple tablespoons of salsa in the bottom of an 8x8-inch baking dish and spread over the bottom. Cut the block of cream cheese into thirds, then cut each third into small cubes.
Place the ground beef in a large skillet and set over medium heat. Break the ground beef into small pieces with a wooden spoon. Brown the beef for 5 minutes, then add in the taco seasoning and 2/3 cup water. Stir well, and simmer for another 2 minutes to thicken the sauce. Turn off the heat.
Spread several handfuls of Doritos over the bottom of the baking dish. Press them down, breaking the chips, to create an even layer. Spread one-third of the taco meat over the broken chips. Then top with one-third of the cream cheese cubes, 1 cup shredded cheese, and one-third of the remaining salsa.
Repeat with a second and third layer of pressed Doritos, taco meat, cream cheese cubes, 1 cup of shredded cheese, and salsa. Sprinkle the remaining shredded cheese over the top to cover the other ingredients.
Bake for 25+ minutes, until the cheese is melted and the chips around the edges are very crisp. Sprinkle the top with chopped scallions. Cut the taco lasagna into 9 squares and serve warm!