Mix the pears, cranberries, ginger, and lemon juice in a large bowl.
Add 2/3 cup sugar and cornstarch and stir into the fruit.
Pour the filling into the pie shell. Invert the top pastry over the filling and press the edges together. Trim the pastry flush with the edge of the pan and crimp.
Cut several steam vents into the top OR before topping cut shapes out of crust with small cookie cutter (maple leaf and acorns shapes or holly leaf shapes are cute).
Lightly brush on the milk and sprinkle 1 teaspoon sugar (or more if desired).
Bake for 30 minutes. Reduce the oven temperature to 375. Watch crust for browning. If crust gets too dark cover with pie shield or foil. Bake until the juices bubble thickly, 25 to 30 minutes more. Cool 2 hours.