Preheat oven to 180°C (Gas mark 4/350°F). Grease and line a 30cm x 20cm (12in x 18in) rectangle cake tin.

Place the butter and caster sugar in a large bowl and whisk together until well combined and fluffy.

Add the eggs, two at a time, whisking after you add each pair. Once the eggs have all been whisked in, add the flour, vanilla extract and milk. Whisk again until fully combined.

Pour the cake mixture into the prepared cake tin. Gently smooth the top down with a spatula, then bake in the pre-heated oven for around 35 minutes, until golden and springy to the touch.

Once the cake is cooked, transfer to a wire rack and leave to cool completely before decorating.

Once the cake is completely cold, prepare the whipped cream:

Whip the double cream in a bowl with the vanilla extract and icing sugar until thick and fluffy.

Spread the whipped cream in a thick layer over the top of the cake, taking it right up to the edges and keeping it as neat as possible.

Wash and hull the strawberries, then cut them in half lengthways.

Arrange the strawberries on the top of the cake in a cross shape. Add the raspberries in lines to form the diagonal cross. Fill in the gaps with triangles of blueberries.

Pop in the fridge until ready to serve.