Preheat the oven to 200°C.
Place all the crumble ingredients in a bowl and rub together with the tips of your fingers. Once all the ingredients are incorporated and you have a fine crumble, spread on to a baking tray and bake in the oven for 20 minutes.
Break the chocolate into pieces and place in a heatproof bowl. Melt the chocolate over a pan of simmering water. Set aside and allow to cool to room temperature.
Use an electric whisk to whip the cream until thick. Carefully fold in the chocolate. Chill in the fridge for 30 minutes.
Peel the bananas and cut in to very small cubes.
Wash then zest and juice the lime into a bowl. Add the brown sugar, the seeds from the vanilla pod and the rum. Add the chopped banana and mix gently.
To serve, remove the chocolate mousse from the fridge and whisk again so that it is thick and creamy - be very careful not to over-whisk the mousse as it will turn and become too liquid. Place the mousse in a piping bag with a star nozzle.
Place a little of the banana in each verrine. Top with the chocolate mousse and then finish with a sprinkling of spiced hazelnut crumble.
«Be very careful when making the mousse, it is important not to over-whip the cream when adding the warm melted chocolate.»