New England Clam Chowder

Name: New England Clam Chowder
Ingredients: 4 slices thick cut bacon; 3 stalks celery ( chopped); 1 large Spanish onion ( chopped); 1 large garlic clove ( minced); 4 medium waxy potatoes ( peeled and cubed); 14.5 ounces chicken broth; 8 ounces bottled clam juice; 1 teaspoon fresh ground black pepper; 1 teaspoon fresh thyme leaves ( or 1/4 teaspoon dried); 3 tablespoons cornstarch; 2 cups half-and-half ( divided); 2 6 1/2 ounce cans chopped clams (rinsed and drained); fresh parsley leaves ( chopped)