Caramelized Onion, Gruyere, and Walnut Tart – Valley Walnut

Ingredients

• 1 package frozen puff pastry, thawed
• 3 tbsp olive oil
• 2 large onions
• 1 tsp sugar
• ½ tsp salt
• ¼ tsp black pepper
• ½ pound of Gruyere cheese
• 2 large eggs
• 1 cup heavy cream
• 2 tsp fresh thyme leaves
• 1 cup of walnuts