Cut chicken into quarters or eighths. Soak chicken, refrigerated, in buttermilk for several hours or overnight. In a large brown paper bag combine 1 cup of the flour with paprika, cayenne pepper, oregano, thyme, cumin, coriander, salt, and pepper. Toss the chicken in remaining cup of unseasoned flour, dip again in buttermilk, and then toss in the bag with the seasoned flour. Reserve 2 tablespoons of seasoned flour.
In a large cast iron skillet over medium heat, heat 1/2-inch oil to 245 degrees on a fryer thermometer. In batches, carefully add several pieces chicken and fry until golden brown on both sides, about 20 minutes. Cover chicken after turning. Check for doneness with a fork. Place cooked chicken in 325 degree oven to keep warm while finishing remaining chicken.
After all the chicken has been cooked, pour off all of the oil except 2 tablespoons to make the gravy. Add reserved 2 tablespoons seasoned flour to cooking oil and cook for 3 minutes until medium brown. Whisk hot milk into flour and cook for 2 minutes. Serve finished gravy with chicken.