Preheat the oven to 325 degrees . Spread 1 cup chopped walnuts on a rimmed baking sheet. Bake until lightly browned, 5 to 8 minutes. Let cool. Roll each crust out on a lightly floured surface into two 12-inch circles. Using a 4-inch round biscuit cutter, cut out 12 circles. Working with 1 round at a time, crimp the edges by pinching together about every half inch, then gently press into the cups of a 12-cup muffin pan coated with cooking spray.
In a medium bowl, whisk the eggs, brown sugar and salt until smooth. Whisk in the butter, cornstarch, bourbon and vanilla. Stir in the toasted walnuts.
Divide the chocolate chips among the piecrusts in the muffin pan, then fill each with the walnut mixture (about 2 tbsp. each). Top each with a walnut half.
Bake the pielettes until the filling feels set when gently pressed, about 30 minutes. Let cool in the pan. Run a knife around the edges to release pielettes from the pan. Transfer to a platter. Top with whipped cream.