Debone chicken thighs and cut into small chunks that fit your grinder
Place chicken pieces on a cookie sheet and freeze for 1-1.5 hours until partially frozen
Grind the partially frozen chicken with skins through an 8 mm plate
Mix all spices together: kosher salt, sugar, powdered buttermilk, black pepper, nutmeg, onion powder, garlic powder, sage leaves, and parsley flakes
In a large bowl, combine ground chicken with spice mixture, diced onions, cold chicken broth, and cayenne pepper
Mix very well until the mixture becomes sticky and tacky
Stuff the sausage mixture into hog casings, packing slowly to remove air pockets
Twist the sausage into 6-inch links
Refrigerate overnight to allow flavors to develop
Preheat grill to 400°F
Insert meat probe into the thickest part of the thickest sausage
Cook sausage until internal temperature reaches 165°F, turning once during cooking
Remove from grill and serve
