Step 1

Line the base and sides of a 20cm/8in square cake tin (not loose-based) with greaseproof paper and butter the paper. Set oven to 180C/Gas 4/fan oven 160C.

Step 2

Cream the butter and sugar together until light. Gradually beat in the eggs, adding a little flour towards the end to prevent curdling. Beat in the lime zest, then fold in the flour and almonds. Fold in enough lime juice – about 3 tablespoons – to give you a good dropping consistency (the mixture should drop easily from the spoon when tapped).

Step 3

Fold in three quarters of the blueberries and raspberries and turn into the prepared tin. Smooth the surface, then scatter the remaining fruit on top – it will sink as the cake rises.

Step 4

Bake for about 1 hour (cover with foil if beginning to brown too much), or until firm to a gentle prod in the centre. A skewer pushed into the centre should be clean when removed.

Step 5

Meanwhile make the syrup: put the lime juice, zest and sugar in a small saucepan. Put over a gentle heat and stir, without allowing to bubble. The sugar should dissolve a little. As soon as the cake comes out of the oven, prick all over with a skewer then spoon the syrup over it. To store, cool before wrapping in paper and/or foil.

Step 6

Carefully remove the cake from the tin, discard the lining paper and cut into 12 pieces to serve.