Combine the pancetta, brown sugar, sage, thyme, paprika, allspice and cayenne in a food processor. Pulse until the pancetta is finely chopped.
Transfer the pancetta mixture to a large bowl; set the bowl in a larger bowl of ice. Add the ground chicken and pork, parsley, 2 teaspoons salt, a generous amount of black pepper and the heavy cream. Mix with a rubber spatula until the cream is incorporated into the meat.
Transfer the meat mixture to a small rimmed baking sheet; press into a 9-by-12-inch rectangle. Cover with plastic wrap and refrigerate at least 2 hours or overnight.
Preheat the oven to 375 degrees F. Bake the sausage until lightly browned and cooked through, 25 to 35 minutes. Pour off any excess fat and transfer the sausage to a cutting board. Cut into pieces, top with thyme and serve with maple syrup.