Begin the recipe by preheating the oven to 350 degrees F. Using a large skillet over medium-high heat, add the 1 tablespoon olive oil and allow it to heat thoroughly.
Add the 1 pound chicken, ½ teaspoon salt, and ½ teaspoon ground black pepper. Allow the chicken to cook until it is no longer pink, about 3 to 5 minutes. Remove the chicken from the skillet and allow it to cool for a few minutes before cutting it into small pieces if needed. Set aside.
Using a large pot over medium-high heat with heavily salted water, bring it to a boil before adding the 1 pound oif pasta. Allow the pasta to cook until al dente, about 4 to 6 minutes. Carefully strain off the water and set the cooked pasta aside.
In that same skillet that you cooked the chicken, add the 3 tablespoon butter and allow it to melt and become foamy. Add the ¼ cup all-purpose flour and whisk continuously for about 2 to 3 minutes.
Slowly pour in the 28 ounces enchilada sauce and continue whisking until the sauce is heated and bubbly. Add the 4 ounces cream cheese and stir until fully combined.
Add the 1 medium diced red bell pepper, ¼ cup green onion, cut-up chicken, and cooked pasta to the skillet. Stir until everything is coated with the sauce.
Pour the mixture into a 9x13-inch baking dish lightly sprayed with cooking spray. Spread the pasta in an even layer in the baking dish.
Evenly top with the 1 ½ cups shredded cheese and place into the oven to bake for about 15 to 20 minutes, until the cheese is melted and slightly golden.
Carefully remove the pasta from the oven. Feel free to top it with some additional green onions and a dollop of sour cream before serving warm. Enjoy!
If you have any leftovers, cover them with a lid, plastic wrap or aluminum foil, or transfer them to an airtight container, and store them in the refrigerator for up to 4 days.