Preheat your oven to 180°C (350°F) and line a baking tray with parchment paper.

Cream together softened unsalted butter and caster sugar until light and fluffy.

Incorporate the large eggs one at a time, mixing well after each addition, followed by the vanilla extract.

Sift in the self-raising flour and gently fold it into the mixture until just combined.

For the frangipane filling, beat together softened butter and caster sugar until creamy, then add eggs, ground almonds, and almond extract.

Spread the frangipane mixture over the cake base evenly.

Toss the chopped rhubarb with a little sugar and scatter it evenly over the frangipane layer.

Bake in the preheated oven for 35-40 minutes or until golden brown and a skewer comes out clean.

Allow to cool in the tray for about 10-15 minutes before transferring to a wire rack to cool completely.

Dust with icing sugar before serving.