Heat Olive Oil in 12-inch skillet over medium heat and cook garlic 30 seconds. Add mushrooms and cook, stirring occasionally, 2 minutes or until mushrooms are tender. Add Swiss chard and cook until wilted; drain and set aside.
Evenly spoon Sauce over focaccia. Top with Swiss chard mixture, cheese, rosemary, salt and pepper. Bake 10 minutes or until cheese is melted. Serve hot or at room temperature.