peeled, pitted, and sliced fresh peaches
a 9-inch graham cracker or baked pastry pie shell
a generous grating of fresh nutmeg
Combine half the peaches with the sugar, water, and cornstarch in a saucepan and bring to a boil over moderate heat.
Simmer until the mixture has thickened and the peaches are tender, about 20 minutes.
Mash the peaches with a wooden spoon to form a coarse puree.
Place the remaining peaches in the pie shell and pour the pureed peach mixture over them.
Combine the sour cream, sugar, and vanilla, stirring to mix thoroughly. Pour over the peaches, top with the nutmeg, and bake in a preheated 350F (180C) oven for 10 minutes.
Allow to cool to room temperature and refrigerate until chilled, at least 2 hours.