Caramelized Onion Quiche

Ingredients

• pie dough
  1 unit
• olive oil
  2 tablespoons
• – 3 large red onions (about one pound total)

  French-cut (see below)
  2 unit
• salt and freshly ground pepper
  1 unit
• balsamic vinegar
  1 teaspoon
• milk
  ½ cup
• heavy cream
  ½ cup
• eggs
  3 large
• nutmeg
  1 pinch
• Gruyère cheese

  grated (1½ cups)
  6 ounces