Roll out half the pastry and line a 9-inch pie pan. Arrange the pear slices in layers in the pastry-lined pie plate, sprinkling the sugar mixture over each layer.
Dot with butter and sprinkle with lemon juice. Roll out the remaining pie dough for the top crust. Use your fingers dipped in a small bowl of water to moisten the rim of the bottom crust.
Place top crust over filling, and trim edge using kitchen shears or a sharp paring knife. Fold the edge of the top crust under the bottom crust, pressing to seal.