Preheat the oven to 350°F. Oil or butter an 8 or 9-inch square baking dish.
In a mixing bowl, toss the sliced peaches with the ground ginger and maple syrup until coated. Place mixture into the baking dish.
Mix together the oats, flour, brown sugar, salt, cinnamon, and crystallized ginger. Blend in the butter pieces with your fingers or a pastry cutter until crumbly. Spread the topping evenly over the peaches. Bake for about 45 minutes, until peaches are bubbling and the crisp topping is lightly browned. Let the crisp set for 15 minutes before serving.
This classic summertime dessert is often served with ice cream or sweet tea with mint—a festive way to end any barbecue or picnic.