To make this taco pasta casserole, start by preheating your oven to 375 degrees and spraying a 9 x 13 pan with non-stick spray.
Next, bring a large pot of water to boil and cook your pasta, minus 2 minutes from the cooking time on your pasta box. Drain your pasta and set aside.
While your pasta is cooking, begin browning the ground beef in a large skillet over medium-high heat until no longer pink. Drain grease and move meat to a plate or bowl and set aside.
Add butter to the same skillet and when melted, whisk in the all purpose flour. Let cook while whisking for 1-2 minutes. Pour in milk and chicken stock and whisk to combine with the flour mixture. Bring to a low boil.
Stir in spices, taco seasoning and enchilada sauce. Add in most of your cheese, remove from heat and stir until cheese has melted. Add the meat and pasta to the skillet with your cheese sauce and stir to combine. Transfer to the prepared 9 x 13 pan and sprinkle top with remaining cheese.
Bake for 20 minutes, remove and let sit for 10 minutes. Sprinkle with green onions and serve immediately.