In a large oven safe skillet, melt the butter and onions on med-high and cook 10 mins.
Slowly add the wine in 3 additions, letting it cook into the onions each time.
Cook another 10 mins until caramelized.
Add the garlic, salt/pepper and cook 3-4 mins.
Add broth.
Increase to high and then reduce to a low boil.
Add meatballs and cook 10 mins.
Drizzle in the cream and stir.
Place bread slices on a baking sheet, brush lightly with olive oil, sprinkle with salt and toast at 450 6-8 mins.
Turn on broiler.
Lay bread on the meatballs, top with cheese and broil until browned. Top with parsley.