Caramelized Onion Focaccia

3 large sweet onions, thinly sliced
2 tablespoons butter
salt and pepper, to taste
1 tablespoon marsala or other cooking wine, sherry, port or sweet vermouth
2 tablespoons brown sugar
focaccia bread, store-bought crust or refrigerated pizza dough
grated Parmesan cheese

Melt butter in skillet. Add onions and cook until tender. Season with salt and pepper. Add marsala and brown sugar and allow to simmer until thick and caramelized. Spread over focaccio or other crust. Sprinkle with Parmesan cheese. Bake at 375 until onions are bubbly and cheese melts.

NOTE: This recipe can also be used as a main dish.