Preheat the oven to 350 degrees. In a small bowl combine the salt, pepper, cumin and chili powder. Mix to fully combine.
Heat a large skillet over medium-high heat. Add the butter to melt. While the butter is melting, rub all sides of the chicken breasts with the spice mix using it up.
When the butter has melted, lower the heat to medium and place the chicken breasts into the skillet. Allow the breasts to cook uncovered for 3 minutes; flip and cook on the opposite side for 3 more minutes.
Remove the skillet from the heat and cover. Allow chicken to sit undisturbed for 8-10 minutes (if using thicker breasts they will take 10 minutes or even 12 minutes). After the time has elapsed cut into the breast to check for doneness. The chicken should be cooked through but very moist. If chicken is done, shred by hand and set aside. If not replace the lid and allow it to sit a few more minutes until cooked through then shred. Reserved pan juices.
Reheat the skillet on medium heat. Add the onion and garlic, cooking until translucent about 4 minutes.
Add the corn, beans, green chilies, chipotle chilies, ¾ cup of the enchilada sauce and the shredded chicken. Bring to a low boil and allow to cook for 5 minutes, stirring occasionally to allow absorption of the liquid.
While the mixture cooks, spoon ¾ cups of enchilada sauce on the bottom of a 9 inch by 13 inch baking dish. Spread to cover the bottom.
Prepare the tortillas: to make the tortillas pliable for rolling the enchiladas, place 3 at a time on a medium plate and cover them with a damp paper towel. Heat in the microwave on high for 30 seconds. Repeat with 3 more after rolling 3 enchiladas. Note: I find microwaving the tortillas in small groups and using them before microwaving more keeps them warm and supple.
Preparing the Enchiladas: Mix the cheeses together in a large bowl. Spoon 1/3 to ½ cup of filling into the middle of a prepared tortilla, making a line down the center spanning the width of the tortilla. Sprinkle with 2 tablespoons of cheese. Gently fold one edge of the tortilla that is not covered with filling over the filling and then the opposite side over the middle enclosing the filling. Turn the enchilada upside down and place it seam down in the pan horizontally. You’ll be making two rows of 6 across the width of the pan (and if making them with less filling, can squeeze two more horizontally end to end between the two rows if desired; if so ensure the rows of 6 are touching the ends of the baking dish to allow room in the middle). Repeat until all the enchiladas are prepared.
Spoon on the remaining enchilada sauce covering the tops of the enchiladas fully. Sprinkle on the remaining cheese evenly over the enchiladas. Place in the preheated oven for 15-20 minutes until the cheese has melted and the enchiladas are warmed through.
Serve immediately with options toppings for diners to customize their enchiladas to their liking!