Chicken Pot Pie Soup

Name: Chicken Pot Pie Soup
Ingredients: 3 tablespoons unsalted butter; 1 large yellow onion , chopped (about 2 cups ); 2 small carrots , chopped (about 1 1/4 cups ); 2 medium ribs celery , sliced (about 1 1/4 cups ); 6 large garlic cloves , chopped (about 2 tablespoons ); 1 1/2 teaspoons kosher salt; 1 teaspoon dried thyme; 3 tablespoons all-purpose flour; 6 cups chicken broth; 2 cups shredded chicken (from 1 rotisserie chicken); 2 cups chopped red potatoes (about 4 potatoes ); 2 cups frozen peas (from one 16-ounce bag); 1/2 cup half and half; 2 cups oyster crackers; 1/4 cup olive oil; 1 teaspoon kosher salt; 1/4 teaspoon cayenne pepper (optional)