In a medium saucepan, bring chicken broth to a boil. Stir in rice, reduce heat to low and cover; simmer 15 minutes. Meanwhile, heat olive oil in a medium skillet over medium heat. Add garlic; sauté 30 seconds. Stir in onions; sauté 2 minutes, add mushrooms, and continue to cook for 5 minutes or until mushrooms are soft. When rice is ready, remove lid, increase heat to medium and stir in evaporated milk. Cook for 5 minutes, stirring frequently, until rice is thick and creamy. Remove from heat and stir in mushroom mixture and Parmesan cheese. Season with salt and pepper, if desired. Serve immediately.