Scatter an even layer of sponge crumbs (or bread-roll/croissant crumbs) over the bottom of a buttered heatproof dish.
Arrange a thick layer of pitted, halved plums on top, then sprinkle generously with cinnamon sugar and ground almonds, and drizzle with a little cream.
Repeat the layering (crumbs – plums – cinnamon sugar and almonds – cream) 1-2 more times, until the dish is full.
Whip the 5 egg whites with the 5 tablespoons of sugar into a stiff, glossy meringue.
Spread the meringue evenly over the top, or pipe it on, so it fully covers the plums.
Bake in an oven preheated to 170-180 °C for 25-30 minutes, until the meringue is a nice golden brown and the plums are soft.
Serve warm or cold.
Based on: Malatinszky Fanny szakácskönyve (a classic Hungarian cookbook), modernised. Calories and protein are estimated.