1. Preheat the oven to 350°F (180°C). Line a 6 cup terrine mold or loaf pan with the bacon slices, letting the ends of the bacon hang over the sides of the dish.

2. Pulse the chicken livers in a food processor until finely chopped. Transfer to a bowl. Add the veal, pork, butter, sherry, onion, garlic, oregano, and allspice and season well with salt and pepper. Mix with your hands until combined.

3. Transfer the meat mixture to the terrine mold and fold the bacon ends over the top. Cover tightly with the lid or aluminum foil. Place the dish in a roasting pan and add enough hot water to come halfway up the sides of the dish.

4. Bake for 1½ hours, until a meat thermometer inserted in the center reads 165°F (74°C). Transfer the terrine in its mold to a baking sheet. Replace the foil with a fresh sheet. Place another pan to fit inside the terrine, and fill with heavy cans of food. Refrigerate for 24 hours. Unmold, slice, and serve.