Measure the milk in a heavy saucepan; split the vanilla bean, scrape the seeds into the milk and add bean into the pan

Simmer for 5 minutes at about 50°C; remove from heat, cover, and set to infuse 10 to 20 minutes

Meanwhile, scale the sugar into the TM bowl and add yolks; insert the butterfly and beat until pale for 10 seconds at speed 4

With the time set for 10 seconds and the speed at 4, add the flour through the hole in the TM lid

Strain the milk that has steeped in the saucepan gradually into the egg mixture

Set the time for 4 minutes and the temperature at 100°C; bring mixture to a boil at speed 4 and cook one minute (you will have to watch when the mixture comes to a boil and adjust time accordingly)

Stir in the liqueur, if using

Strain into a bowl and cover with plastic wrap; set aside to cool (this is Crème Pâtissière)

When chilled, whip the cream and gently fold it in (this is now Crème Mousseline)

Spread the cream evenly in the base of the tart; arrange the berries neatly over top

Put the milk in a saucepan; split the vanilla bean, scraping the seeds into the milk, and add bean into the pot

Heat to a simmer, remove from heat, cover, and set to infuse 10-20 minutes

Beat the yolks with the sugar until pale; beat in the flour

Pull the vanilla bean from the milk and whisk the milk gradually into the egg mixture; pour back into the saucepan

Bring to a boil, and cook one minute; remove from the heat and stir in the liqueur, if using

Strain into a bowl and cover with plastic wrap; set aside to cool (this is Crème Pâtissière)

When chilled, whip the cream and gently fold it in (this is now Crème Mousseline)

Spread the cream evenly in the base of the tart and arrange the berries neatly over top