This is best eaten warm with runny cream or vanilla ice cream. You can make it in advance and reheat it in the oven, just keep it in the cake tin and cover with tinfoil before reheating.
8 rhubarb stalks, trimmed, cut into 4cm lengths
zest and juice 1 orange
3 tablespoons caster sugar
4 large slices sourdough, crusts discarded
4 large croissants
25 grams butter, softened
¼ cup apricot jam
2 large eggs, size 7
3 egg yolks
75 grams caster sugar
1 teaspoon vanilla paste
60 grams hazelnuts, roasted, skins removed (see Cook’s note)
20 grams raw sugar
20 grams butter, melted
Equipment: Line a baking tray with baking paper. Line a 20cm springform cake tin with baking paper and tightly wrap the exterior of the tin in foil; the custard is runny to start with and the foil will stop any custard from leaking into the oven.
Preheat the oven to 180°C.
Cake: In a bowl, combine the rhubarb, orange zest and juice and caster sugar. Place on the prepared baking tray and bake for 15 minutes, or until the rhubarb has softened. Set aside to cool.
Place the slices of bread on a piece of baking paper. Spread both sides with butter and one side with jam. Cut into 3cm chunks. Cut the croissants crosswise into 2cm-thick slices.
Arrange a third of the sourdough chunks and croissant slices neatly into the base of the prepared cake tin. Top with one-third of the roasted rhubarb. Repeat the steps to create three layers. Reserve the juices from rhubarb pan.
Custard: In a bowl, whisk together custard ingredients and carefully pour over the cake.
Place the cake tin on a baking tray and bake for 20 minutes.
Hazelnut topping: Halve the nuts and place in a bowl with the raw sugar and butter.
Scatter over the cake and return to the oven for 10-15 minutes. Leave the cake in the tin to cool slightly and set before removing. Drizzle over the reserved rhubarb juices just before serving.
Cook’s note: To remove the hazelnuts skins, roll the roasted nuts between your hands; the skins will flake off.