Autumn Tart

Ingredients

• 1 tbsp unsalted butter
• 1 tbsp extra virgin olive oil
• 1 cup leeks (washed and sliced crosswise)
• 1/2 tsp kosher salt
• 1/4 cup heavy cream
• 1 splash dry white wine
• 1 juice of lemon
• 1/2 cup leek cream sauce
• 1 pkg puff pastry (thawed)
• 8 oz oyster mushrooms (trimmed, rinsed and dried)
• 10 swiss chard leaves
• to taste kosher salt
• all-purpose flour (for dusting )