Flemish Caramelized Onion Tart - Michigan Onion

Ingredients

• 3 cups All-purpose flour
• 1 tsp. Kosher/Sea salt
• 6 tbsp. Cold butter, cut into small cubes
• ¼ cup Cold rendered pork/bacon fat or vegetable shortening, cut in pieces
• ½ cup Ice water
• Aluminum foil
• pie weights or dried beans (for blind-baking)
• 4 tbsp. butter, cut into chunks
• 3 lbs. yellow onions, peeled, cored, and julienned
• kosher/sea salt and freshly-ground black pepper, to taste
• freshly-grated nutmeg, to taste
• 1 tsp. fresh thyme leaves
• 2 large eggs
• ½ cup heavy cream
• 1 cup shredded Gruyère cheese (Comté cheese is also commonly used)