Heat oven to 400°. Put flour, sugar, ginger, salt and cinnamon into bowl of food processor fitted with metal blade. Process to mix. Cut butter into small pieces and sprinkle over flour. Process until mixture resembles course crumbs.

Refrigerate 1/2 cup of the crumb mixture for topping. Pat remaining crumb mixture evenly over a 10" round tart pan with removable bottom. Put pan onto baking sheet. Bake until golden brown, about 20 minutes. Remove from oven; cool on wire rack.

Reduce oven temperature to 350°. Drop peaches into a large pot of boiling water for 30 to 60 seconds. Cool by running under cold water. Remove skin. Cut peaches in half and remove pits. Cut each hald into 1/4" thick slices. Arrange slices over cooled crust.

Mix remaining ingredients in medium bowl. Carefully pour over peaches. Sprinkle with reserved crust. Bake until filling is set and crumbs are slightly golden, about 40 to 50 minutes. Cool on wire rack. Seve warm with whipped cream, if desired.