Flaky Caramelized Onion Tart with Gruyère Cheese - Recipes by Lena

Ingredients

• 200 g all-purpose flour
• 100 g cold unsalted butter, cut into cubes
• 1 egg
• Pinch of salt
• 1-2 tbsp cold water
• 3-4 large onions, about 500 g, thinly sliced into half-rings
• 30 g unsalted butter
• 100 ml heavy cream (20-30%)
• 2 eggs
• 100 g hard cheese, grated (e.g., Gruyère, Parmesan, or Cheddar)
• Salt and pepper, to taste
• A pinch of nutmeg (optional)