Beat together the butter with the sugar until light and fluffy.
Add in the eggs, ground walnuts, flour and beat until smooth.
Stir in the melted chocolate.
Spoon the mixture over the pastry and smooth it gently with a pastry knife.
Peel the pears and cut them in half length-wise.
Remove the cores and slice each half length-wise into thin slices.
While keeping each of the sliced halves together, place them over the chocolate filling. (As seen in the photo)
Bake in a preheated oven at 350 degrees F, for about 45 minutes or until the walnut mixture is firm and the pastry is golden brown.
Transfer to a wire rack to cool then dust with powdered sugar just before serving.