In a large mixing bowl, combine flour, sugar, and salt. Add cold butter and mix until coarse crumbs. Gradually add cold water and vinegar until dough forms. Chill for at least 2 hours.

Preheat oven to 425°F (220°C). Roll out chilled dough into a pie dish, line with parchment and weights. Bake for 15-20 minutes until golden. Let cool.

Heat milk in a saucepan. In a bowl, whisk yolks and sugar, then mix in cornstarch and flour. Gradually add hot milk while whisking. Return to heat and cook until thickened, about 5-7 minutes.

Layer sliced bananas in the cooled crust, pour pastry cream over the bananas, smooth the top, cover with wrap, and chill for 3-4 hours.

In a bowl, whip heavy cream, mascarpone, and powdered sugar until stiff peaks form. Spread over the chilled pie.

Smooth the Chantilly cream over the pie and optionally decorate with lemon-brushed banana slices.