Dr. Pepper Barbecue Sauce

INGREDIENTS

• 1/3 cup Worcestershire sauce
• 1/2 cup packed dark brown sugar
• 1 cup ketchup
• 4 cloves garlic, chopped
• 4 tablespoons (1/2 stick) unsalted butter
• 1 teaspoon kosher salt
• 1 large yellow onion, chopped
• 1/2 cup cider vinegar
• One 12-ounce can Dr. Pepper
• 2 teaspoons ancho or New Mexican chili powder
• 3 tablespoons tomato paste
• 1 teaspoon fine-ground white pepper