First things first, line a 20cm square baking tin with greaseproof paper and set aside.
To make the base, blitz vanilla biscuits in a food processor or crush with a rolling pin. Add melted butter and mix through thoroughly. Press biscuit mix firmly into base of prepared tin and place in the fridge to cool while you make the filling.
In a large saucepan, add the cream, milk, sugar, cornflour and butter. Slowly bring to a boil and stir constantly for about 3 minutes until it thickens. Remove from the heat, then quickly whisk in the egg yolks and vanilla until silky and smooth. Pour over top of biscuit base, smooth surface and then return to the fridge to set and cool for about 3 hours.
When the slice has set, remove from fridge and slice into 12 squares. Sprinkle each square with roughly half a tablespoon of sugar before carefully heating, caramelising and giving colour to the melting sugar with a blowtorch.
Either serve immediately or return to the fridge until required. Crack!