Place the pork, olive oil, shallots, onion, all but six sprigs of the thyme, three bay leaves, the remaining spices, and the salt in a large, non-reactive bowl and toss so that all is thoroughly combined. Cover and refrigerate for 24 hours.
Remove the bay leaves and the thyme sprigs from the pork. Purée the liver in the food processor, add it to the pork, and stir gently until all the ingredients are thoroughly combined. Cook a teaspoonful of the mixture in a hot skillet to taste for seasoning, remembering that when the pâté is chilled its seasoning will be muted. Adjust the seasoning if necessary. Stir in the nuts until they are thoroughly combined.
Preheat the oven to 350°F (175°C).
Place three of the bay leaves and three generous sprigs of thyme on the bottom of an 8 cup (2 liter) porcelain terrine mold, or other non-reactive container. Add the Top the pork mixture, smoothing and pressing it into the terrine, then top that with the remaining three sprigs of thyme, and the remaining bay leaves. Top with parchment paper and then either the lid of the terrine mold, or a piece of aluminum foil. Place the terrine mold into a pan large enough to hold it with room to spare and pour in boiling water half-way up the sides of the terrine mold. Bake until the terrine is cooked through and registers about 170°F (75°C) on a meat thermometer inserted into the center of the terrine, about 2 hours.
Remove from the oven and let cool. Place at least three 1pound (500 g) weights on the parchment paper atop the terrine, to weight it down, and when it has reached room temperature refrigerate it for at least 24 hours. Serve chilled, with plenty of cornichons alongside.
About 10 servings