Cut the grapefruit choux biscuit into 28 x 52 cm pieces and spread 350 g of grapefruit confit on the surface.
Pipe 13 x 52 cm long strips of vanilla mousseline using a 1 cm diameter round nozzle tip.
Fold both edges of the biscuit to the center, overlapping the vanilla mousseline.
Keep in the freezer for 30 minutes then cut the biscuit into 3 cm thick pieces.
Prepare an almond crust as the base and pipe a line of grapefruit confit on top.
Place the grapefruit roulade on the base and garnish along the side.
Pipe orange blossom Chantilly on top of the roulade using a star nozzle.
Finish by decorating with red amaranth and grapefruit confit.