Preheat oven to 400ºF. Lightly grease a 12-cup muffin tin and set aside.
Cut 12 even squares from the rolled out puff pastry sheet and place a square into each muffin cup. Lightly brush each puff pastry square with egg wash.
Fill each cup with pears and bake until pastry is golden and puffed up, about 15-20 minutes. Top with blue cheese and walnuts and return to the oven until cheese has heated through and walnuts have toasted, about three to five minutes.