Caramelized Onion & Gruyere Tart | Flour & Fig

Ingredients

• 1 sheet of puff pastry - approximately 9.5"x10.5"
• 4 cups sliced yellow onions (650g)
• 1 tbsp olive oil (8g)
• 2 tbsp butter (28.5g)
• 1 tsp salt (6g)
• 1/4 tsp each ground nutmeg and black pepper (1g)
• 2 egg yolks
• 1/2 cup whipping cream (120g)
• 1 cup grated gruyere cheese(100g)
• 1 tbsp Dijon mustard (15g)
• 2 tbsp grated gruyere to sprinkle on the top prior to baking