Step 1
Cut chicken thighs into 1-inch pieces. Chop pancetta finely using a meat cleaver until paste-like in texture. Mix chicken and pancetta together. Sprinkle salt pepper thyme fennel coriander cayenne nutmeg and sage. Mix until combined and place mixture on a plate; cover with plastic wrap and freeze for 15 to 20 minutes before grinding.
Step 2
Peel and quarter apples. Grate apples into a bowl. Place grated apples in a paper towel and squeeze all the water out. Add apples to the partially frozen chicken sausage meat.
Step 3
Place 1/2 of the chicken mixture in a food processor. Pulse on and off until mixture is slightly finer than coarse sausage. Repeat with the remaining chicken. Cover with plastic wrap and refrigerate to let the flavors develop 4 hours to overnight.
Step 4
Use a large ice cream scoop to portion out the meat. Flatten scoops with dampened hands to make patties about the same size as your biscuits.
Step 5
Heat oil in a large skillet over medium-high heat. Cook patties until bottom is browned and leaves a deep brown fond in the skillet 3 to 5 minutes. Reduce heat to medium and flip patties over. Add butter and sage leaves. Cook until patties are firm to the touch removing leaves once they stop bubbling about 5 minutes more. Remove patties.
Step 6
Whisk flour into the pan; cook and stir until starting to thicken about 1 minute. Pour in broth and bring to a boil whisking the browned bits of food off the bottom of the skillet. Add maple syrup and creme fraiche; season with salt and pepper. Cook until gravy is spoonable and reaches desired thickness 2 to 3 minutes more. Add more broth if gravy is too thick. Remove from heat.
Step 7
Place biscuit halves on individual plates. Top each with a chicken sausage patty; spoon gravy on top. Garnish each with a fried sage leaf.