Step 1 In a small saucepan, bring the cider to a boil, then reduce to a good simmer. Cook until the cider reduces to one-fourth cup, 6 to 8 minutes. Remove from the heat and add the bouillon cube, stirring until the cube dissolves. Place the mixture in a glass container and refrigerate until chilled.
Step 2 In a large bowl, toss the chicken with the salt, black pepper, sage, ginger, cinnamon and nutmeg. Cover the bowl and place the chicken in the freezer just until it begins to stiffen, about 30 minutes.
Step 3Remove the chicken from the freezer and grind with a meat grinder fitted with a three-eighths-inch grinding plate into a large bowl set over an ice bath. Once the chicken is ground, stir in the reduced cider, diced apples and onion. Knead and squeeze the mixture until well blended.
Step 4Fry a small patty until done to check the flavor and seasoning (it should be cooked to an internal temperature of 165 degrees). If necessary, adjust salt, pepper and other seasonings, then fry another small patty and check again.
Step 5Divide the sausage into 7 or 8 portions (each about one-half pound). Alternatively, stuff the sausage into the casing, following the manufacturer's instructions for your sausage stuffer; tie into 5-inch links. Refrigerate the sausage up to 2 days, or freeze up to 2 months.