In a saucepan over medium heat, add the milk and half the sugar.
In the bowl of a stand mixer, add the egg yolks and the remaining sugar. Mix.
Add the flour and the cornflour to the same bowl, all at once.
Add a little milk to loosen the mixture.
When the milk starts to boil, pour it into the egg and sugar mixture.
Return everything to the pan over medium heat and stir until the cream thickens.
Cover with cling film touching the surface and chill for 30 minutes.
Take the cream out and beat it again to loosen it.
Add the butter little by little.
The cream will lighten in colour and firm up.
Finally, add the praline paste.
The cream is ready when it holds its shape without collapsing.
Chill the cream for 30 minutes, then pipe.