Blackberry & Lime Cake with Walnut Streusel Topping

I made this cake a couple of weeks ago for my grandads birthday. I had just been blackberrying and so was primed with lots of fresh berries to use. I decided to pair them with some lime zest as I think this helps bring out the berries natural zing and sweetness. The amount of lime zest stated in the recipe may seem small, but it’s amazing how much flavour this small amount provides, it really was quite apparent in the finished cake.

It’s an unusual cake in that when it comes to mixing in the flour you are actually after a slightly lumpy batter as over mixing it will result in a dense heavy cake. In this respect it’s more like a muffin mix where the little lumps of flour help give the crumb its airy texture and springiness. My grandad is also diabetic (diet controlled) so I liked the fact that the recipe didn’t contain too much sugar and that it made use of a nutty streusel topping instead of a buttercream or frosting.

The streusel topping bakes into a delicious crispy crumbly topping and the added nuts get a gentle toasting making them even more flavoursome and nutty. The cake itself was studded with the blackberries which were full of flavour and added little pockets of bright purple juiciness. It was delicious when served slightly warm – we even reheated slices the next day in the microwave, the perfect accompaniment to a cup of afternoon tea.

Blackberry & Lime Cake with Walnut Streusel Topping

(Recipe adapted from Delia Smith)

Cake

250g blackberries
Zest of ½ lime
275g plain flour
1 tsp baking powder
½ tsp salt
2 eggs
75g caster sugar
170ml milk
110g butter

Streusel

75g plain flour
½ tsp baking powder
25g butter
50g Demerara sugar
50g walnuts
1 tbsp water

Method – Streusel Topping

Place the flour, baking powder and butter into a bowl. Use the tips of your fingers to rub the butter into the flour, lifting it up and letting the mix fall back into the bowl. Continue until you have no large lumps of butter left and the flour is starting to look like crumbs.
Chop the walnuts into small chunks and mix through the flour mixture along with the sugar. Add the water and rub briefly so the mix forms little into little clumps. Set aside until required.

Blackberry Lime Cake

Preheat the oven to 190C. Grease a deep 8inch springform tin and line the base with baking paper.
Whisk the eggs, sugar and milk together until combined and just starting to look foamy. Melt the butter until liquid, then pour into the egg mix and briefly whisk again.
Sift the flour and baking powder over the top and add the salt and lime zest. Mix with a spatula or wooden spoon in a folding motion until no flour streaks remain – it should look lumpy – this is ok – don’t try and beat them out!
Add the blackberries and gently fold them in, don’t mix too much or they will break down, but a few purple streaks are quite pretty.
Pour the cake batter into the tin and scatter over the streusel topping.
Bake in the oven for 1 hour until the top is deep golden brown and a skewer inserted in the middle comes out clean.
Allow to cool in the tin for 30 minutes before removing from the tin and leaving to cool to room temperature.
Delicious served still warm with cream or crème fraiche
Serves 8-10