Keep the hearts and bacon cold. Trim large tough vessels or connective tissue from the hearts and cut the hearts, bacon, and mushrooms into pieces that fit the grinder or processor.

Grind the chicken hearts, then the bacon. Feed 2 mushrooms through last to move the remaining meat out of the grinder path.

Mix briefly and grind the mixture a second time, feeding the remaining 2 mushrooms through last. The mixture should be fine, cohesive, and evenly marbled without large chunks.

Add the basil, sea salt, black pepper, oregano, garlic powder, onion powder, and crushed fennel seed. Mix until evenly speckled with no pockets of seasoning.

Cover in a nonreactive bowl and refrigerate for 24 hours.

Heat the oven to 250°F. Line a rimmed stainless sheet pan with parchment. Divide the cold mixture into small, evenly sized meatloaf-style logs, press out deep cracks, and space them apart.

Bake for 4 hours, until the logs are set and browned outside and fully cooked through with no raw, wet center.

Cool for about 1 hour, then refrigerate in a covered container until thoroughly chilled.

Slice the cold logs thinly with a sharp knife and serve as salami-style slices.