Rio Grande Enchilada Casserole

This was the third place winning casserole dish that Tim made for the contest.  It was delicious!

Rio Grande Enchilada Casserole

3 pounds boneless, skinless chicken breasts
Kosher salt
4 tablespoons olive oil
2 tablespoons unsalted butter
2 serrano chiles ( seeds and stems removed, diced)
2 cloves garlic (minced)
2 tablespoons all purpose flour
2 cups chicken broth
2 cups sour cream
1 cup chopped cilantro
1 teaspoon ground cumin
1 dash cayenne
1 can (11 oz.) tomatillos ( drained)
24 corn tortillas
10 ounces Monterey Jack ( grated 2.5 cups)
1 medium onion (diced)

1. Preheat oven to 350 degrees F. Season chicken with salt and pepper, toss with 2 tablespoons oil, and bake in a cast-iron skillet until cooked through, about 30 minutes.  Let cool, shred , and set aside.

2. Meanwhile, in a large pot over medium-low heat, melt butter.  Add chiles; cook until soft, about 4 minutes.  Add garlic; cook for 1 minute.  Whisk in flour for 1 minute.  Whisk in broth until thickened, about 6 minutes.  Stir in sour cream, 1/4 cup cilantro, cumin, and cayenne.   Transfer to a blender, add tomatillos, and puree.  Pour 1 cup mixture in each of 2 buttered 9x13 inch baking dishes.

3. In a large skillet over medium heat, heat 1 1/2 teaspoons oil and cook tortillas in batches until soft, about 1 minute per side, adding oil as needed.  Place 1/4 cup reserved chicken, 1 tablespoon cheese, and 1 teaspoon onion on each tortilla and roll into a cigar shape. Place in baking dishes and cover with remaining sour cream mixture and cheese.  Bake until top is lightly browned, about 25 minutes.  Garnish with remaining cilantro.