Preheat oven to 350° F. Place cherries and cognac in a small mixing bowl. Set aside.
Heat olive oil and butter in a small fry pan set over medium-low heat. Add the onion and cook until onion is very soft and transparent, about 10 minutes. Add the garlic, thyme, paprika and allspice. Cook until garlic is fragrant, about 1 minute. Remove pan from heat and allow to cool completely.
Finely mince 4 slices bacon (or use a food processor) and set aside. Line a terrine mold with the remaining bacon slices, slightly overlapping the slices to completely cover the bottom and sides of the mold (about 18 slices).
Strain the cognac from the cherries and pour into a large mixing bowl. Add the onion mixture, minced bacon, ground pork, eggs, heavy cream, salt and pepper. Using a spatula or hands, gently stir together until well combined.
Using hands or an offset spatula, place 1/2 of the meat mixture into the terrine on top of the bacon slices, pressing it down into an even layer. Evenly distribute 1/2 of the cherries and pistachios over the meat, then place the chicken strips in a single layer on top of the fruit and nuts. Sprinkle with the remaining cherries and pistachios in an even layer on top of the chicken, then top with the remaining meat mixture. Press meat down to completely fill terrine mold, including into the corners. It may seem like too much meat, but it will cook down.
Fold the bacon slices over the top of the meat, using additional bacon slices if needed to completely cover the meat. Place the whole bay leaves on top of the bacon. Place the lid on the terrine mold (the lid may not fit snuggly at this point). Set terrine mold on a rimmed baking sheet and place in preheated oven. Bake for 1 hour. Carefully remove the lid and bake for 30 minutes longer to evaporate some of the liquid and slightly crisp the bacon on top.
Remove the terrine from the oven and allow to cool slightly. Carefully pour or skim off any accumulated fat and juices, and discard. Cut a piece of cardboard that is the same size as the interior of the terrine and cover the cardboard completely with foil. Place on top of the terrine (directly on top of the bacon) and weigh down with a Dutch Oven, skillet or a few heavy cans. Place weighted terrine mold in the refrigerator and chill at least 8 hours, or overnight.
To unmold, use a long spatula to lift terrine out of mold, or flip over onto a plate. Remove and discard bay leaves and slice terrine into slices for serving.