In a large oven proof skillet, melt butter with the onions until lightly caramelized, then add in the fresh garlic and saute for about 1 minute on medium heat.Add in the beef broth, salt, pepper and the heavy cream into the onion/garlic mixture and stir to combine.Allow it to slightly begin to bubble, then add in the parmesan cheese and stir.Add in the sliced zucchini and cook an for an additional 5 minutes until softened..Top with your cheese of choice evenly across the entire top and bake at 425F for about 12-15 minutes or until the cheese begins to brown to your liking.ENJOY!