Make the cookie dough: cream together the butter and sugar then add the mint, food colouring, salt and flour. Lastly, add the finely chopped choc chips and stir through. Divide the dough into three, and shape each one into a square between two sheets of greaseproof paper. Make them the same size as your serving dish, then pop into the fridge to chill for 30 minutes.
Make the mousse: whisk the cream to soft peaks then add the icing sugar and mix through. Slowly add the dissolved gelatine and then whisk to firm peaks, then stir through the chopped Oreos.
Make the ganache: warm the cream to a gentle simmer then pour it straight over the finely chopped chocolate. Whisk until smooth.
Assemble the lasagne: put a quarter of the mousse into the serving dish and spread it around, evenly. Add a quarter of the ganache and spread that out too, then carefully lay a layer of cookie dough on top. Repeat until all of the fillings are used up, finishing with a layer of mousse then ganache. Chill for 2 hours then serve wedges topped with extra whipped cream, mint syrup and extra chopped Oreos.
