Leek Tart - The Local Palate

Ingredients

• pie crust dough or refrigerated roll out pie crust
• 1 tablespoon oil
• 1 tablespoon butter
• 3 leeks, cleaned and thinly sliced, white and light green parts only
• 1 tablespoon mustard
• 3 eggs
• ½ cup heavy whipping cream
• ½ cup gruyere cheese, freshly grated
• Salt and freshly ground black pepper
• ½ teaspoon fresh thyme