• Cut the rhubarb into 2 cm pieces. Place the rhubarb in a saucepan with 50 ml of water and 25 grams of sugar.
• Boil the rhubarb for 10 minutes until soft, it is nice if the rhubarb is not completely cooked to a pulp. Drain the rhubarb, but save the rhubarb juice (you'll be dipping your long fingers in it).
• Separate the eggs. Beat the egg whites until stiff, adding the remaining 25 grams of sugar in while beating.
• Melt the chocolate in a double boiler. Fold the melted white chocolate into the mascarpone. Gently fold in the beaten egg whites.

Build the tiramisu

• Dip the lady fingers in the rhubarb juice and place them on top of the mascarpone until the dish is completely covered, then spread half of the rhubarb compote on the lady fingers.
• Cover the dish with the rest of the mascarpone, crush the pistachios (you can do this in a coffee grinder or mag mix, or chop them as finely as possible with a knife).
• Grate the rest of the white chocolate. Spread the remaining rhubarb over the tiramisu and sprinkle with the pistachios and white chocolate pieces. Allow to set in the refrigerator for (at least) 3 hours.