Puree the fruits (except for a few nice specimens for later decoration) together with the lemon juice with the blender. If you take frozen fruits, you should either let them thaw or you can also put a tablespoon of hot water in the blender, this will make it easier to puree.
Whip the cream until stiff, then mix the yogurt and mascarpone in a bowl together with the lemon juice and finally fold in the whipped cream.
Roughly break the speculoos into small pieces.
Now layer everything in a nice glass, starting with the mascarpone cream, adding some of the speculoos and the pureed fruits on top. The liquid will later soften the biscuit. Then put the cream on it again, etc. until all the ingredients are used up. It is best to end on top with a dollop of mascarpone and finally drape the fruits that were previously set aside. If you like, you can put in a little piece of mint or decorate the whole thing with a little cinnamon or cocoa powder.