Heat the oven to 400°F.  Line a baking sheet with parchment paper.
Place the pastry cups onto the baking sheet.  Stir the syrup and walnuts in a small bowl.  Brush the tops of the pastry cups with the syrup mixture.
Bake for 20 minutes or until golden brown and puffed.  Using the end of a wooden spoon handle, press the centers of the hot pastry cups down into the bottoms of the cups.
Beat the heavy cream, sugar and vanilla extract in a medium bowl using an electric mixer on high speed until soft peaks form. Spoon or pipe the cream mixture into the pastry cups.