Heat the oven to 375° F.
Some candied ginger comes in small pieces, but if using larger pieces, chop the ginger into small pea- sized pieces. Place the ginger pieces on a cutting board and chop with a knife.
Wash and slice the peaches and place into a large bowl. You can peel the peaches if you like. I leave the peel on. You will need about 5 cups of sliced peaches. Place the fruit in a large mixing bowl and stir in the lemon juice.
In a small bowl, mix the brown sugar, cornstarch, candied ginger, ground ginger, and nutmeg. Add this mixture to the fruit and lightly toss until combined.
Pour the fruit into the pie plate. Dice the butter into very small pieces and then dot the fruit with the butter.
Place the pie dough onto the top of the fruit, then cut the excess dough around the pie plate with a paring knife. See notes below.
Tuck the dough inside the rim of the pie plate. Place the pie plate on a baking sheet to catch any drips and put it in the oven and bake for 30 minutes.
Remove the baking sheet from the oven and using a sharp knife cut 1-inch squares into the pie crust. Now with the back of a spoon press down on the edges of the squares so the juices start to cover the crust. You don't have to do all the squares but make sure the filling can bubble up over most of the crust. Sprinkle the top of the crust with decorator's sugar and return to the oven and bake for 25 minutes. The peaches should be tender with the juices bubbling over the pie crust and most likely the rim of the pie plate.
Let the pandowdy cool for about 20 minutes before serving. Cover any leftover with foil or plastic wrap for several days.