If shell puffs during baking, press it down with back of spoon. Cool on wire rack. Lower temperature to 3. Prepare filling In a medium saucepan over medium high heat, reduce maple syrup by a quarter, 5 to 7 minutes. Stir in cream and bring to a simmer. Remove from heat. In a medium bowl, whisk together egg yolks and egg. Whisking constantly, slowly add cream mixture to eggs. Strain mixture through a fine mesh sieve into a cup or bowl with pouring spout. Stir in salt, nutmeg and vanilla. Pour filling into crust and transfer to a rimmed baking sheet. Bake until pie is firm to touch but jiggles slightly when moved, about 1 hour. Let cool to room temperature before serving.