Barbecued Shrimp with Cheese Grits

Name: Barbecued Shrimp with Cheese Grits
Ingredients: 2 tablespoons unsalted butter; 1 small onion, cut into 1/4-inch dice; 2 garlic cloves, very finely chopped; 1 1/4 cups ketchup; 1/4 cup bourbon; 3 tablespoons cider vinegar; 2 tablespoons molasses; 2 tablespoons honey; 2 teaspoons Tabasco; 1 teaspoon chopped thyme; 1/2 teaspoon cayenne pepper; Kosher salt and freshly ground black pepper; 1 1/2 pounds peeled and deveined large shrimp; 1 tablespoon vegetable oil; Cheese Grits , for serving