Peel the apples and cut into fine wedges. Butter a baking dish and layer the apple wedges. Drizzle with lemon juice and calvados.
Heat the butter until it is runny. Mix all remaining ingredients thoroughly, pour over the melted butter and fold in. Spread this crumble mixture over the apples.
Put the tin in the cold oven and bake at 180 ° C for about 30 minutes.