Halve peaches. Crumble a few ginger snaps. Mix them with the crystallized ginger (it's already in little pieces I assume), a little bit of flour, and some rolled oats and brown sugar (or substitute granola). Add nuts if desired (do slivered almonds go with ginger?). Put a pile of crumble mix on each peach half. Top with a few small dabs of butter. Bake till peaches are soft.
Google "crumb-top" or "peach crumble" to get a basic idea about the amounts of flour, oats, butter to use if you haven't made a crumb topping before. It's a pretty forgiving dessert.