Working in batches, place the chicken in a food processor and pulse until coarsely ground, probably 6 to 8 pulses. Transfer to a large bowl.
Dump the bacon and butter in the food processor and pulse until coarsely ground, at least 6 times and perhaps 12 times.
Add the bacon and the butter to the chicken and stir by hand until combined. Add the apples and stir again.
In a spice mill or coffee grinder, grind the coriander seeds, fennel seeds, and peppercorns together to a medium-fine grind. Add the ground spices to the chicken mixture along with the salt, nutmeg, and cayenne. Mix with your fingertips until well blended.
Pinch off a small amount and heat it in a little oil in a skillet over medium-high heat, turning once, until cooked through. Taste and adjust the seasonings in the uncooked sausage mixture accordingly.
To make patties, using your hands, shape the sausage mixture into 12 to 15 patties, each about 3 inches (7 1/2 centimeters) in diameter and 1/2 inch (12 millimeters) thick.