1.
Preheat the oven to 200°C. Combine the zest, juice, rhubarb and sugar in a dish in a single layer. Cover and bake for 15-20 minutes until tender. For toast, beat the eggs, cream and vanilla in a shallow bowl.
2.
Melt half the butter in a large non-stick frypan over medium heat. Dip half the brioche in the egg mixture, allowing any excess to drain off. Cook for 1-2 minutes on each side until golden, then keep warm in the oven while you repeat with the remaining brioche.
3.
Divide toast among plates, then spoon over rhubarb and serve with custard or cream.