Core the peaches and cut into thin slices. Mix with blueberries, sugar and nutmeg. Drizzle with lemon juice. Put in a greased baking dish.
In a bowl, mix the egg whites with the brown sugar, melted butter, the crumbled amarettini and the oatmeal. Process these ingredients into a crumbly mass and pour over the fruit.
Bake in the preheated oven at 175 ° C for about 45 to 55 minutes - until the peaches are soft.