01 -
Whisk egg yolks with caster sugar for 2–3 minutes until light and thick, then whisk in cornflour. Pour milk into a saucepan, split vanilla pod lengthways, scrape seeds into milk, and add the pod. Bring milk to boil then remove from heat. Pour hot milk in a slow stream onto egg mixture, whisking continuously.
02 -
Return mixture to a clean saucepan and whisk continuously over medium heat, ensuring to scrape sides and bottom to prevent burning. Once the cream thickens and releases a bubble or two, remove from heat.
03 -
Pour custard into a wide bowl to cool to room temperature. When cooled, transfer to a large piping bag with a 1cm nozzle, place in a jug to keep upright, and refrigerate for 1–2 hours.
04 -
Preheat oven to 180°C (fan). Line baking tray with parchment. Cut puff pastry into 12 rectangles measuring 4cm x 10cm and arrange on tray. Brush lightly with beaten egg and sprinkle with caster sugar.
05 -
Cover glazed rectangles with baking paper, then place another baking tray on top to prevent pastry from rising. Bake for 30 minutes.
06 -
Meanwhile, toss rhubarb pieces in caster sugar and place in a small baking dish. Bake in oven on a shelf below the pastry for 20 minutes until tender but not mushy.
07 -
Pipe 2 blobs of custard onto each serving plate. Place a pastry rectangle on top, then arrange 3-4 rhubarb pieces on the pastry. Gently position another pastry rectangle over the rhubarb. Pipe 2 lines of custard on the second rectangle and top with a third rectangle. Repeat to make 4 millefeuilles.
08 -
Dust with icing sugar and serve immediately.