A wonderful cake that should be left alone for a couple of days before eating

Serves 10

120g unsalted butter, plus more for the tin

125g black treacle

100g golden syrup

150ml milk

120g light muscovado sugar

225g plain flour

1 tbsp ground ginger

1/2 tsp bicarbonate of soda

2 eggs, lightly beaten

3 brandy snaps, lightly crushed (optional)

Lime buttercream

150g icing sugar, sifted

100g unsalted butter, softened

finely grated zest and juice of half a large lime

Preheat an oven to 180 degrees/gas mark 4. Butter a 20cm, 7.5cm deep, square tin and line with baking parchment.

Place the treacle, syrup, milk, sugar and butter into a pan and very gently melt together. Do not let this boil or it will curdle. Remove from the heat and cool a little.

In a large bowl, sift together the flour, ginger and bicarbonate of soda. Add the treacle mixture and fold together with a large spoon. Lastly, add the eggs, mix well and pour the batter into the tin. Knock a couple of times on a work surface to release any bubbles, then bake for 40-50 minutes until firm to the touch and a skewer inserted into the centre comes out clean.

Cool in the tin for about 15 minutes, then turn out on to a rack. When the cake is absolutely cold, wrap it in baking parchment and then in foil and leave for a couple of days. This will make it very moist with a slightly sticky surface.

When ready to serve, make the lime buttercream. Place the icing sugar and butter in the bowl of an electric mixer (or use a bowl and a handheld whisk) and beat for a good five minutes. Tip in the lime zest and slowly pour in the juice, still beating. Spread the buttercream over the cake. Scatter with the brandy snaps, if using.

From Bake & Decorateby Fiona Cairns, published by Quadrille (£19.99). Photograph by Laura Hynd