Zesty Cheesy Chicken Casserole

Preheat oven to 350 degrees.
Cook chicken breasts, dice, and set aside.
Melt butter in olive oil in a small skillet and add onions and garlic. Cook until soft and translucent.
Combine soup and milk in a medium bowl and stir in onions, garlic, green chiles, diced tomatoes, and one cup of shredded cheese. Set aside.
Cook pasta shells until al dente and drain.
Return cooked pasta to the pot and stir in chicken.
Add soup mixture to the pot and combine well.
Add salt and pepper to taste.
Pour mixture into a greased casserole dish and top with the remaining cup of cheese.
Bake for 30 minutes or until cheese is melted and casserole is bubbly.