Stuffed Lettuce Leaves in Broth (Lattughe Ripiene in Brodo)

Ingredients

• 1 oz. dried porcini mushrooms, rinsed
• 2 slices country-style Italian bread, about 1/4" thick, crusts removed
• ¹⁄₄ cup milk
• salt
• ¹⁄₄ lb. veal sweetbreads
• 2 tbsp. butter
• 1 yellow onion, peeled and chopped
• 1 clove garlic, peeled and minced
• ¹⁄₂ lb. veal loin, coarsely chopped
• 1 bay leaf
• Freshly ground black pepper
• 2 tbsp. pine nuts, toasted
• 1 tbsp. finely chopped fresh parsley
• 1 tbsp. finely chopped fresh oregano
• ¹⁄₄ cup freshly grated parmigiano-reggiano
• Pinch freshly ground nutmeg
• 1 egg plus 1 egg yolk, lightly beaten
• 3 heads butter lettuce, washed and separated
• 8 cups rich chicken stock, warm