oil in skillet on medium heat. Add onions and season with salt and pepper. SautÉ for
3 minutes or until softened. Turn heat to low, stir in balsamic vinegar and sugar
and sautÉ for 10 minutes longer or until onions are a browned, thick mass.
oven to 400ºF(200ºC). Combine olive oil and garlic and brush on mushrooms.
Combine onions with half of cheese. Fill caps with mixture and top with remaining
cheese. Bake 12 to 15 minutes or until mushrooms are soft and cheese is melted and slightly golden.
Combine arugula, olive oil and balsamic
vinegar in a bowl. Season with salt and pepper. Place mushrooms on 4 plates.
Surround with arugula and top with shaved parmesan.