Grease and line an 8 inch tin, you need to line the sides too this is important to get a clean edge on the tart and to make it easy to remove.
Start with the base; you need to make a praline by adding the sugar to a frying pan and melting it over a medium heat, do not stir the sugar as crystals will form, just swirl the pan from time to time.
When you have achieved an even amber colour remove the caramel from the heat and stir in the hazelnuts.
Pour the mix immediately onto a lightly greased baking sheet or lightly oiled stainless steel work surface, basically the caramel will set and you want to make sure it won’t stick.
After 5-10 minutes when the caramel is set, snap off roughly a third and keep for the topping,
Add the rest to a food processor, with the cornflakes and pulse to a fine powder, add a splash of water to bind the mix, not too much you only want to slightly wetten it, a few tbsp. is enough.
(Back in the old days when my nana made this she didn’t have a food processor so she used a tea towel to wrap and a rolling pin to smash up the praline, you can use whatever you prefer and have to hand.)
Press this mix tightly into the prepared tin and pop it in the fridge while you make the topping. You can, and I have eaten the base on its own, cut into chunky fingers dipped in chocolate or jam.
For the topping bring the milk and cream to the boil.
Once boiled remove from the heat and add the chocolate stirring off the heat until all the chocolate has melted. Next stir in the eggs nice and quick, the mix will become glossy and smooth.
Pour over the chilled base and set in the fridge anything between 4 hours and overnight.
150g caster sugar
150g hazlenuts, toasted and skinned
A dash of warm water
300mls double cream
100ml whole milk
300g 70% cocoa chocolate, smashed into small pieces