Slit the vanilla pods lengthways and scrape out the seeds. Mix the mascarpone, quark, vanilla seeds, and sugar until smooth.
Crumble the amaretti biscuits into bite-sized pieces.
Combine the amaretto liqueur with the cold espresso in a small jug.
In a serving bowl, layer the first third: biscuits, drizzle 2 tablespoons of amaretto-espresso, spread 1/3 of the mascarpone cream, and scatter 150 g (half) of the raspberries.
Layer the second third: repeat the previous step with the remaining second portion of each ingredient and the remaining 150 g raspberries.
Top with the final 1/3 of the mascarpone cream, spreading it evenly.
Just before serving, dust the surface with cocoa powder.
For frozen raspberries: prepare 1-2 hours ahead to allow them to thaw and chill the cream.