In a large skillet, cook the bacon over medium low heat until crisp. Remove to drain on paper towels, then crumble. Drain away all but about 2 tablespoons of the bacon grease, then return the pan to medium heat. Add the onions and cook, stirring occasionally, about 5 minutes or until translucent. Add the mushrooms and cook, stirring occasionally, for 5 minutes or until the mushrooms are golden brown. Add the garlic and cook for 1 minute. Stir in the undiluted mushroom soup and add the crumbled bacon back. Stir to combine. Stir in the milk and cheese. Stir until the cheese is melted. Add salt and pepper to taste. Fold in the green beans until well combined.