Heat 1 teaspoon neutral oil in a large, high-sided skillet (at least 11 inches wide) or Dutch oven over medium-high heat until shimmering. Add 1 finely chopped small yellow onion and cook, stirring occasionally, until translucent and slightly softened, about 4 minutes.
Add 1 pound lean ground beef and cook, breaking it up into small pieces with a wooden spoon, until cooked through and browned, 6 to 8 minutes. Stir in 1 (1-ounce) packet taco seasoning and 2 tablespoons tomato paste, and cook until fragrant and the tomato paste is slightly darkened, about 2 minutes.
Stir in 3 cups water, 1 (10-ounce) can red enchilada sauce, 1 (10-ounce) can diced tomatoes and green chilies and their juices, and 1 pound dried elbow macaroni noodles. Bring to a boil over medium-high heat. Continue to boil, stirring the pasta frequently to prevent sticking, until the noodles are al dente and the liquid has reduced to a thick, creamy sauce, 7 to 11 minutes.
Remove the skillet from the heat. Stir in 2 cups shredded cheddar cheese, ½ cup coarsely chopped sliced American cheese, and 4 ounces cubed cream cheese until fully melted. Taste and season with salt as needed. Serve with desired toppings.
