Soak the gelatine leaves in a small bowl, with just enough cold water to cover, for 5-10 minutes until soft.
Pour the cream liqueur, cream and milk into a large, wide saucepan and slowly bring to the boil over a medium heat.
Meanwhile, beat the egg yolks, sugar, cornflour and vanilla extract together in a large jug until smooth and well blended.
Remove the cream mixture from the heat as soon as it comes to the boil and gradually pour it into the egg mixture, stirring all the time.
Return the whole lot to the saucepan and bring o a gentle simmer over a low heat, stirring constantly until thickened enough to coat the back of the spoon.
Remove from the heat. Squeeze the excess water from the now-softened gelatine and stir in the mixture until dissolved.
Pop a piece of cling film directly on the surface to prevent a skin from forming and leave to cool completely.
To make the chocolate chip cups: line the muffin tin with the cases.
Snap the chocolate into a medium heatproof bowl and melt either in the microwave in 30 second blasts, stirring between each go, or over a pan of simmering water, shallow enough that the water doesn’t touch the bowl. When melted, stir and remove from the heat.
Spoon a tablespoon of melted chocolate into a paper case and use a small brush to spread it from the bottom up the insides to coat completely.
Repeat with the other nine cases.
About three-quarters of the chocolate should remain so set this aside for now.
Pop the muffin tin in the freezer for 20 minutes, until the cups are set.
Repeat the process of coating with chocolate and freezing to set three more times, to give four layers in total,
The melted chocolate will cool to room temperature, which is perfect for adding layers without melting the previous layer (if you work quickly), but it should not be allowed to set.
If it doesn’t, then melt it again as before, but very briefly not letting it become too warm.
Once the four layers are complete and set, and with cool hands, carefully peel the paper cases away from the chocolate to reveal the fluted cups.
Arrange them on a tray lined with parchment paper as you go.
Divide the now cooled filling evenly between the chocolate cups, levelling the tops.
Chill in the fried for at least 4 hours until completely set. These can be made up to a day in advance.
If you haven’t already made the hazelnut praline, now is a good time to do so.
When ready to serve, dust the crème brulee filling with cocoa powder through a fine sieve.
Break the praline into ten chunks and stick one upright in the top of each cup.
Serve on a pretty little palate.