1. Take the raspberries out of the packaging and let them thaw slightly.

2. Melt the butter in a small pot over low heat.

3. Meanwhile, put the oat biscuits in a freezer bag and crush them finely with a rolling pin. Tip: You can also use a blender to crush them.

4. Add the cookie crumbs and salt to the butter and mix well.

5. Line the bottom of a large heart-shaped baking pan or a round springform pan (26 cm diameter) with baking paper.

6. Place the butter-crumb mixture into the form and press it down firmly using a spoon or the bottom of a glass.

7. Wash the lemon, dry it, and finely grate some of the skin. Squeeze out the juice from the lemon.

8. Purée the raspberries with the lemon juice. Tip: Don't purée for too long, or it will become bitter due to the seeds.

9. To remove the seeds, pass the raspberry puree through a fine sieve into a small bowl. Tip: Press through the sieve with a large spoon or ladle.

10. Stir the instant gelatin into 100 ml of whipped cream. Tip: The liquid should not be ice-cold. If lumps form, mix with an immersion blender.

11. Smooth the mascarpone and fold in the gelatin mixture and raspberry puree.

12. Whip the remaining cream with the sugar until stiff and fold it in. Season the cream with lemon zest and sugar. Tip: If desired, you can intensify the pink color with a few drops of red food coloring.

13. Spread the cream over the prepared base and smooth out. Chill for at least 3 hours, or preferably overnight, to set.

14. Run a damp knife around the edge to loosen the cake from the pan, then carefully place it on a platter. Arrange fresh raspberries on top. Grate white couverture using a coarse grater or a vegetable peeler and sprinkle it decoratively on the cake. Tip: If you place the couverture in the freezer for about 10 minutes, it will be easier to grate.