Instructions:
Preheat oven to 350° F.  Lightly butter a 4-quart shallow baking dish.

To make topping, in a small bowl, combine ½ cup cheddar, breadcrumbs, Parmesan and paprika.  Toss with 4 tablespoons melted butter and set aside.

In a large sauté pan, over medium heat, melt 1 tablespoon butter with olive oil.  Stir in scallions, chili powder, oregano, garlic, salt, pepper and diced chilies.  Cook for 3 minutes, stirring frequently.  Reduce heat to low.  Gently stir in chicken and cook, about 2 minutes, until heated through.  Remove from heat, transfer to a large bowl; set aside.

Bring 4 quarts of water to a boil.  Add 1 tablespoon salt and pasta.  Cook according to package directions, stirring occasionally.  Pasta is done when it is slightly chewy to the bite or al dente.  Drain pasta in a colander and fold into chicken mixture.

Prepare sauce while pasta is cooking.  In a large saucepan, melt remaining butter over medium heat.  Whisk in flour and cook for 3 minutes, whisking constantly.  Gradually add milk and bring just to a boil, whisking constantly.  Reduce heat and simmer, stirring often, until sauce begins to thicken, 4-5 minutes.  Add pepper jack and remaining cheddar.  Stir until cheese is melted. Remove from heat. Gently fold sauce into chicken/pasta mixture.
 
Spread mixture evenly in prepared baking dish. Top with reserved breadcrumb mixture.  Bake for 20-25 minutes until bubbly and top begins to brown.  Let sit 5 minutes before serving.  
 
Prep: 45 min.
Baking: 20-25 minutes