New England Clam Chowder

Name: New England Clam Chowder
Ingredients: 2 ounces bacon fat; 2 ounces butter; 1 large onion, diced; 6 stalks celery, diced; 1 tablespoon garlic, minced; 1⁄2 shredded carrot (optional); 1⁄2 cup flour; 1⁄2 cup instant mashed potatoes; 4 chef potatoes, peeled and chopped; 1 quart clam juice; 3 cups chopped clams; 1 1⁄2 cups half-and-half; 1⁄4 cup fresh parsley, chopped; 1 drop Tabasco sauce; 1⁄2 teaspoon celery salt; 1⁄2 teaspoon thyme; 1 bay leaf; 2 tablespoons chopped parsley (garnish)