Step 1: Cook the Pasta and Prep the Pan - Bring a large pot of salted water to a boil and cook the pasta shells until al dente according to the package directions. Drain and set aside. While the pasta cooks, preheat the oven to 375 degrees and lightly grease a 9x13 baking dish.
Step 2: Sauté the Vegetables - Heat the olive oil in a large skillet over medium high heat. Add the diced onion and green chiles and cook for 2 to 4 minutes until the onion softens and becomes fragrant.
Step 3: Add Garlic and Spices - Stir in the minced garlic, cumin, chili powder, salt, and pepper. Cook for about 30 seconds until fragrant, stirring constantly so nothing burns.
Step 4: Build the Roux - Add the butter to the skillet and let it melt completely. Sprinkle in the flour and whisk continuously for about 1 minute to cook out the raw flour taste.
Step 5: Create the Sauce - Slowly pour in the heavy cream and chicken broth while whisking to prevent lumps. Lower the heat and let the sauce thicken slightly.
Step 6: Add the Cheese - Stir in one full bag of Monterey Jack cheese until melted and smooth. Add half of the second bag and stir again, reserving the rest for topping.
Step 7: Combine Everything - Add the cooked pasta, shredded chicken, corn, and beans to the sauce. Gently stir until everything is evenly coated.
Step 8: Bake Until Bubbly - Transfer the mixture to the prepared baking dish. Sprinkle the remaining cheese on top and add extra corn if desired. Bake for about 30 minutes until golden and bubbly.
Step 9: Serve and Enjoy - Let it cool slightly before serving. Top with cilantro if desired and dig in.