Clam Chowder with carrot

12 tablespoons unsalted butter , divided 2 cups yellow onions , chopped (2 onions) 2 cups celery , medium-diced (4 stalks) 2 cups carrots , medium-diced (6[...]

3 tablespoons butter 3 medium carrots , peeled and diced 1/2 medium onion , peeled and diced 3 celery ribs , diced 3 -4 crushed peppercorns 4 cups white wine[...]