Tahini and halva brownies

Brownies don't really need improving but when Yotam Ottolenghi speaks, I listen, and I'm glad I did. On the weekend, I made a half batch (why??), cut them up, packed them into a Tupperware and took them on the train down the south coast to a beach buffeted by wind and shared them with shivering friends.

Nutty sesame swirled through gooey chocolate studded with walnuts and little melt in your mouth morsels of halva. There's not much more to say really other than MAKE THEM.

Walnut and halva cake

I set a dangerous precedent. A few years ago, when flying down to see friends in Victoria, I brought a cake in my carry-on luggage. Now, it's not possible to visit without one. The rules of carry-on cake are as follows: no delicate sponges, or sticky icing, no layers or fancy shapes. And by fancy, even round counts here. Loaf cakes only need apply, and sturdy ones at that - the sort I can wrap tightly in tinfoil, stow in a tote bag and slide under the seat in front of me. The sort that will survive take-off, landing and turbulence. The original carry-on cake, lemon yoghurt, fits this brief beautifully, as does the superlative pear, pistachio and chocolate. And now another one to add to my repertoire courtesy of Yotam Ottolenghi: walnut and halva cake.

Halva is a dense yet crumbly confection made with tahini, a mainstay of many cultures from the Middle-east to eastern Europe. My mother used to buy it for us when we were kids to satisfy our craving for something sweet after school. I don't remember having much of an opinion on it then. I'm sure I liked it fine but it was never coveted, more something that would do when we couldn't have what we actually wanted (chocolate! ice-cream! chips!). As an adult, I like it rather a lot. So much in fact that I will only buy small amounts at a time as if it is in my fridge, I will eat it: with coffee, crumbled over vanilla ice-cream, and now, in cake...

This is a beautifully light sour cream cake, embellished with caramelised walnuts and a layer of smooth, sweet halva. It's simple but a little bit special. Easy to carry on, and to carry off.