Preheat the oven to 180°C.
Stone the peaches then roughly slice their flesh.
Add the butter, flour baking powder and sugar in a food processor and blend until you get a mixture resembling breadcrumbs (or just use your fingers!).
Transfer it to a mixing bowl, add rice flakes and the walnuts.
In an ovenproof dish arrange the peach slices, pour over the lemon juice & maple syrup, sprinkle over it the raisins and grate a little nutmeg on top.
Evenly cover the fruit with the crumbs, slightly pressing down with the base of the spoon.
Bake in the oven for about 25 minutes. Before serving, let it rest for about10 minutes - the hot fruit can burn your mouth!
Serve it warm with custard or ice-cream!