To prepare the tart shells, let the frozen pie shells defrost at room temperature for 15 minutes before flattening out on a lightly floured surface. Using a large flower cookie cutter (approx. 4 1/2" in size), cut out 12 flower shapes from the two pie shells and line a 12 cup muffin tin by pressing the dough lightly into the sides, corners and bottom of each cup. Chill the tart shells in the freezer for 15 minutes or until firm to the touch.
Remove from the freezer and blind bake the tart shells by placing a paper muffin cup inside each lined muffin tin and fill halfway with dried beans. Bake in the oven for 12-15 minutes. Remove the paper muffin cup and the beans, rotate the tart shells to ensure even baking and continue to bake for another five minutes or until lightly golden in colour. Remove from the oven and leave to cool completely. Do not remove the tarts from the muffin tins.
To create a leaf garnish for the top of each tart, cut out little leaves using a small leaf shaped cookie cutter from the scraps of dough. Bake on a parchment lined sheet for 10-12 minutes or until the leaves are a light golden colour. Remove from the oven and leave to cool completely.
To make the filling, whisk together the pumpkin puree, condensed milk, sour cream and all the spices in a medium bowl. Add in the eggs and vanilla and whisk until well combined.
Reduce the oven temperature to 325°F. Pour the filling into the cooled tart shells and bake in the oven for approximately 20 minutes or until the filling is set. You can tell the filling is set when the tarts are gently jiggled and the filling does not move.
Remove them from the oven and let cool completely at room temperature before removing the tarts from the muffin tin and serving.
When ready to serve, make the Chantilly cream by placing the 35% cream, vanilla and icing sugar in the bowl of an electric mixer fitted with the whisk attachment and whip to medium stiff peaks. Spoon a dollop of the Chantilly cream on top of each tart and garnish with a leaf.