Crumble can be made with any seasonal fruits and berries, including frozen ones. For peaches, for example, you can add raspberries or currants.
Chop the walnuts into crumbs. Mix flour, brown sugar, baking powder and salt. Put the butter cut into pieces and chop into crumbs. Add those walnuts
Grease the mold generously with oil. Cut the peaches into 6 pieces, removing the pits. Put in a mold, sprinkle with vanilla sugar. Preheat oven to 190°C. Sprinkle the peaches with batter and place in the oven for 30 minutes.
Whip cold cream into foam. Scald the peaches for serving, remove the skin, beat the pulp with powdered sugar and lemon juice with a blender in a puree, mix with cream.
Divide the crumble into bowls, top with cream and serve.