Pre-heat the oven to 350 degrees. In a 9×13” baking dish combine olive oil and garlic. Add the chicken breasts and coat them well on both sides with the oil and garlic.
Sprinkle with red wine vinegar and Cajun seasoning.
Bake for 30 minutes. Remove chicken from the oven and top with green onions and mushrooms. Sprinkle a tiny bit of oil and vinegar over the chicken breasts again. Bake for 15-20 more minutes.
Remove from oven and immediately place 1 slice of Swiss cheese over each chicken breast. Chicken should be hot enough so the cheese will melt.