1. Preheat the oven to 170 degrees Celsius fan oven and line a rectangular baking tin (18cm x 28cm) with parchment paper.

2. Melt the butter, and allow it to cool.

3. Prepare the rhubarb by washing it, shaking off excess water and cutting the stalks into large chunks . Combine the rhubarb with 1 tbsp sugar and place in an ovenproof dish or baking sheet.

4. Cover with a sheet of tinfoil and slowly roast it for 12-15 minutes in the preheated oven, removing it while the rhubarb pieces are starting to soften and before the chunks collapse and lose their shape.

5. Peel, core and cut the apples into chunks (if you do this in advance, toss the chunks in lemon juice to avoid them discolouring).

6. Using an electric whisk beat the eggs, sugar and almond essence together until the mixture is very thick, pale and mousse-like.

7. Gently fold in the melted butter so it is fully dispersed, then fold in the ground almonds (once combined avoid leaving the mixture to sit at this stage or the butter will separate).

8. Pour two thirds of the mixture into the lined baking tray, cover with the baked rhubarb pieces and most of the apple. Pour over the remaining cake batter, then gently press in any remaining apples on the surface.

9. Scatter the flaked almonds over the top. Bake on the middle shelf of the preheated oven for 30-35 minutes, or until just firm to the touch and a skewer inserted into the cake comes out clean. Remove from the oven and allow to cool.

10. Once cool, heat the apricot jam with water, sieve away any pulp and brush the warm apricot syrup liberally over the surface of the traybake. Best eaten within two days.