Truffled mushroom pâté

Name: Truffled mushroom pâté
Ingredients: 50g dried porcini mushroom; 2 tbsp butter; 3 shallots, finely chopped; 250g chestnut mushrooms, finely chopped; 2 garlic cloves, crushed; 250g mascarpone; ½ tbsp white wine vinegar; 30g parmesan or vegetarian alternative, finely grated; 3 tbsp truffle oil; cornichons and toast, to serve; 100g salted butter; 2 tbsp truffle oil; 3 thyme sprigs, leaves picked; ½ tsp green peppercorn, crushed; ½ tsp pink peppercorns, crushed