Bacon, Caramelised onion, Baby spinach quiche – Love and Cook

Ingredients

• 11" pre-baked tart crust
• 2 white onions ( sliced)
• 1 tablespoon olive oil
• 1/2 tablespoon butter
• 1 teaspoon balsamic vinegar
• 200 g smoked bacon cubes ( or smoked pancetta lardons)
• 2 handfuls baby spinach
• few slices tomato ( to decorate, optional)
• 4 eggs ( for the egg component, read notes above)
• 2 cups dairy (1 cup milk, ¾ cup cream, and ¼ cup yoghurt)
• dash nutmeg ( grated on a microplane grater)
• 11/2 tablespoons plain flour
• salt and pepper to taste