Heat the chicken broth in a microwave safe bowl for 1 minute.
In a medium sauce pan, melt butter. Add onion and cook for 7-10 minutes until soft. Whisk in flour and cook for 1 additional minute. Add salt, pepper and cayenne pepper, if desired.
Turn heat up to medium-high and add in warm chicken broth. Cook and stir until think and bubbly, about 2 minutes. Remove from heat.
Stir in cream of mushroom soup and sour cream. Set aside.
Place chicken in a large bowl. Add in 2 cups of sauce, cumin, green chiles and half of cheese.
Stir until blended.
Place about ¼ of filling on each tortilla. Roll up and place in a 9 x 13 baking dish. Pour remainder of the sauce over enchilada. Spread to cover. Top with remainder of the cheese.
Bake for 40-45 minutes at 350 degrees.
