Preheat your oven to 375°F and spray a 9 x 13 pan with non-stick spray.

Bring a large pot of water to boil. Cook the rigatoni, but be sure to subtract 2 minutes from the cooking time listed on the pasta box. Drain and set aside.

In a large skillet over medium-high heat, brown the ground beef until no longer pink. After draining the grease, transfer the meat to a bowl.

In the same skillet, melt the butter and whisk in the flour, cooking for about 1-2 minutes until it turns golden.

Gradually pour in the milk and chicken stock, whisking to combine. Bring the mixture to a low boil.

Stir in the taco seasoning, enchilada sauce, salt, garlic powder, onion powder, and cayenne, if desired.

Remove from heat and mix in the majority of the cheese until melted and creamy.

Stir in the cooked beef and rigatoni until everything is well-coated.

Transfer the complete mixture to your prepared baking dish and sprinkle with the remaining cheese.

Bake for 20 minutes, then let it sit for 10 minutes before sprinkling with chopped green onions. Serve immediately.