Preheat the oven to 200 ° C (top / bottom heat, convection: 180 ° C). Place the morello cherries in a sieve and drain well.
Line the bottom of a baking dish (approx. 20 x 30 cm) with 7 slices of rusks. Mix the sour cream, eggs, milk, sugar and vanilla sugar together. Pour half of the sour milk over the rusks in the tin. Spread 2/3 of the cherries on top. Layer the remaining rusks in the pan like a roof tile and pour the remaining sour cream on top. Spread the rest of the cherries in between.
Bake for about 50 minutes on the lower rail. If the surface gets too dark, cover with aluminum foil. Serve the cherry cherry dusted with powdered sugar while it is still hot.