Caramelized Onion and Capocollo Rye Stuffing

Preheat oven to 325°F. Grease a 3-quart shallow baking dish; set aside. In an extra-large skillet melt 2 tablespoons of the butter over medium-low heat. Add onions, salt, and pepper. Cook, covered, for 13 to 15 minutes or until onions are tender, stirring occasionally. Uncover; cook and stir over medium-high heat for 3 to 5 minutes or until golden. Add beer; cook about 5 minutes more or until liquid is evaporated, stirring frequently. Stir in brown sugar and vinegar. Transfer onion mixture to an extra-large bowl.

In the same skillet melt the remaining 2 tablespoons butter over medium heat. Add celery and leeks; cook about 5 minutes or until tender.

Add celery mixture, bread cubes, capocollo, onion powder, and dry mustard to onion mixture; toss gently to combine. Drizzle buttermilk and broth over bread mixture, tossing gently to moisten. Transfer mixture to the prepared baking dish.

Bake, covered, for 35 minutes. Bake, uncovered, about 30 minutes more or until stuffing is heated through, topping with cheese during the last 5 minutes of baking.