Cardamom marzipan roll with baked rhubarb

Method

1. For the rhubarb, heat the oven to 110°C/90°C fan/gas ¼. Arrange the rhubarb in a shallow roasting tin and scatter over the lemon zest, ginger and sugar with a big splash of cold water. Cover the tin tightly with foil and bake for 1½ hours.
2. Meanwhile make the marzipan. Put the ground almonds, sugars and crushed cardamom in a mixing bowl with a pinch of salt. Mix the egg, almond extract (if using), rum – or orange juice if you want an alcohol- free pudding – and lemon juice in a jug, then make a well in the centre of the almond mixture and pour in the liquid.
3. Mix with a metal spoon, then bring together with your hands. Tip out onto a surface lightly dusted with icing sugar and knead until smooth. Roll into a cylinder about 25cm long, cover with cling film and set aside.
4. Unroll the pastry, keeping it on its paper, with a long side facing you. Place the marzipan on top of the pastry around 2cm in from the edge nearest you, then re-shape it if necessary to fit the length of the pastry. Make 5 equal widthways indents with your finger in the marzipan (giving you six sections), then carefully flip so the indented side is underneath. Bring the near pastry edge over the marzipan, then roll away from you to enclose it, so the indents are on top again. Leave a small (1cm) overlap where the pastry joins, then cut off any excess pastry (see tip). Feel for the indents in the marzipan with your finger and press the pastry down into them.
5. Glaze the top all over with beaten egg, then chill for 30 minutes, still on the pastry paper, uncovered.
6. Remove the rhubarb from the oven and pour the juices into a small pan. Bubble to reduce for around 7-8 minutes until syrupy, then pour back over the rhubarb, cover with foil and keep warm. Turn up the oven to 200°C/180°C fan/gas 6.
7. Transfer the marzipan roll, using the paper, to a baking sheet, glaze again and sift over plenty of icing sugar. Bake for 25-30 minutes until golden and crisp. Remove and cool for around 15 minutes, slice down through the indentations using a serrated knife, then serve with the rhubarb and ice cream.