Preheat oven to 350 degrees F. As you cut them, squeeze a little lemon juice over pears to prevent browning. Combine pears, walnuts and blue cheese; season to taste with salt and pepper. Lay out phyllo sheet and fold in thirds like a letter, lengthwise; brush surface with melted butter. Mound 1/4 of cheese filling at base of folded phyllo sheet and roll up like an eggroll, pinching ends closed to prevent filling from leaking. Brush top with butter and transfer to a baking sheet. Repeat with remaining phyllo and filling. Bake 12 minutes, until golden and lightly crisped. Serve sprinkled with extra walnuts and blue cheese, with a spoonful of pear puree.