RHS Plant & Potato Fair recipe - sweet potato spice cake

Posted by Joe on

RHS Plant & Potato Fair recipe - sweet potato spice cake

A recipe we created for the RHS Plant & Potato Fair 2015. Using sweet potatoes may be a bit of a cheat here, as they’re only a distant cousin of the humble spud, but when grated and paired with spices and maple frosting they make a delectable alternative to carrot cake.

This recipe makes up to 16 slices, so it’s great for a crowd, but to make a smaller cake you can halve the recipe, use a 6×6” (15×15cm) tin, and test after 30-40 minutes.

Sweet Potato Spice Cake

350g plain flour
3 tsps baking powder
1/4 tsp salt
1 tsp ground cinnamon
1/2 tsp ground mace
1/2 tsp ground ginger
375ml vegetable oil (we like to use organic rapeseed)
340g golden caster sugar
4 eggs
300g peeled, grated sweet potatoes
100g chopped pecans
1 tsp vanilla extract
1/4 tsp almond extract
100g desiccated coconut

1. Preheat your oven to 180°c (160°c fan). Grease, line and dust a 9×9” (23×23cm) square cake tin.

2. Beat together the eggs and sugar until pale and creamy.

3. Weigh together the flour, mace, cinnamon, ginger, salt and baking powder, and whisk to combine.

4. Gradually add the oil to the eggs and sugar, and beat until thoroughly combined.

5. Stir in the vanilla and almond extracts.

6. Fold in the flour, followed by the sweet potatoes, chopped pecans and coconut.

7. Pour into the tin and bake for 50-60 minutes. When it’s ready, the centre of the cake should feel firm and offer little resistance when gently pressed by a finger.

8. Leave to cool in the tin for 15 minutes, before turning out onto a wire rack and leaving to cool completely. This cake tastes even more delicious when kept in a tin for a couple of days.

For the maple buttercream frosting:

125g butter (completely softened)
300g icing sugar
100ml pure maple syrup
1/2 tsp vanilla extract

1. Stir together the butter and icing sugar until the mixture looks crumbly, then beat together until smooth.

2. While beating, gradually pour in the maple syrup and vanilla extract. Continue to beat until everything’s completely combined and you have a smooth, beautifully glossy frosting.

3. Spread the frosting over the cake immediately, and decorate with toasted desiccated coconut.