Melt butter in a pot. Fill the biscuits into a large freezer bag and crumble them finely with a rolling pin. Mix cookie crumbs and butter well. Spread the bottom of a square springform pan (24 x 24 cm) with oil. Spread the crumbs evenly and press on. Place the base in a cool place for 10-15 minutes.
Mix mascarpone, curd and sugar with the whisk of the hand mixer. Pour the mixture onto the biscuit base and spread loosely. Chill the cake for at least 6 hours (better overnight)
Wash the plums, grate them dry, halve them and remove stones. Cut plums into slices. Warm the jelly in a pot, remove from heat and let it cool down for about 5 minutes. Mix plums and jelly. Take the cake out of the tin and cut it into rectangular pieces (à 2 x 8 cm). Spread the plums on the pieces and serve
waiting time 6-12 hours