Combine the lukewarm milk, lemon zest, eggs, vanilla sugar and sugar and mix well.
Cut the stale rolls into thin slices.
Arrange the roll slices and cherries in layers in a baking dish greased with butter. Pour the milk mixture over it and let it sit and soak up the liquid for 15 minutes.
Distribute knobs of butter over the top. Bake on the center rack of a preheated oven (200°C, approximately 390°F) for about 30 minutes until golden brown.
Serve dusted with powdered sugar.