Caramelized Onion Tart

Ingredients

• 200 g all-purpose flour
• 100 g cold unsalted butter, cut into cubes
• 1 egg
• A pinch of salt
• 1–2 tbsp cold water
• 3–4 large onions (about 500 g)
• 30 g unsalted butter
• 100 ml heavy cream (20–30%)
• 2 eggs
• 100 g grated hard cheese (Gruyère, Parmesan, or Cheddar all work beautifully)
• Salt
• pepper
• A pinch of nutmeg (optional, but it adds a little magic)