Whip the cream until soft peaks form and refrigerate.
Whip the mascarpone with a mixer at low speed to soften it, then add the melted white chocolate while whipping at low speed (don’t worry if the preparation looks grainy, it will become smooth).
Incorporate the whipped cream into the mascarpone mixture at low speed, then add the vanilla. Mix in the shredded coconut.
Put the cream in a pastry bag.

In another bowl, mix the orange supremes, sugar, and Grand Marnier until the sugar is dissolved.

Assembly:
Put a little cream at the bottom of 6 verrine cups.
Add a few orange quarters and some of their juice on top of the cream, then a biscuit.
Cover again with cream, add a few more orange supremes, and top with a biscuit.
Refrigerate the verrines until serving time.
They can be assembled a whole day in advance.