Preheat oven to 350°F. Heat a Dutch oven over medium-high heat. Cook bacon until crisp. Using a slotted spoon, remove bacon and drain on paper towels. Discard all but 2 Tbsp. bacon drippings. Add onions and cook 3 minutes, stirring frequently, or until soft. Add mushrooms and garlic; cook 5 minutes or until mushrooms are tender. Remove from pan and set aside in a separate bowl. Melt butter in the same pan; whisk in flour and cook, stirring constantly, until light golden brown. Whisk in milk and broth; cook 2 to 3 minutes or until mixture is smooth and thickened. Stir in bacon and mushroom mixture; cook 2 to 3 minutes or until heated through. Remove from heat; stir in soup, cheese, beans and salt and pepper, if desired. Pour into 9 x 13-inch baking dish (3 qt.). Stir; sprinkle with fried onions and bake, uncovered, 30 minutes or until hot and bubbly and onions are golden brown.