Beetroot and chocolate brownies

You can either grate or purée the cooked beetroot before adding to the mix - the latter gives a slightly more velvety texture. They work just as well with or without walnuts. Some people think that a brownie isn't a brownie without walnuts, while others can't stand them; it really depends on your personal preference. Makes 15 squares.

250g unsalted butter, cut into cubes, plus a little more for greasing

250g plain chocolate (about 70% cocoa solids), broken into squares

250g caster sugar

3 eggs

150g self-raising flour (we use wholemeal self-raising)

100g broken walnuts (optional)

250g cooked and peeled beetroot, grated or puréed

Preheat the oven to 170C/325F/ gas mark 3. Lightly grease a baking tin that's roughly 20cm x 30cm in size and at least 2cm deep. Line the bottom with greaseproof paper and butter the paper, too.

Put the cubed butter and chocolate into a heatproof bowl. Place this on an oven tray lined with a baking sheet, and put in oven to warm up. After a few minutes, remove, stir, then return to the oven to melt completely. (Alternatively, melt the chocolate and butter in the conventional manner, in a bowl held over a pan of barely simmering water.)

In another bowl, whisk the sugar with the eggs until smooth and creamy. Stir in the chocolate mixture until well combined. Sift in the flour, stir, fold in the walnuts (if using) and beetroot. Pour into the prepared tin.

Bake for 20-25 minutes, until a knife or skewer comes out with a few moist crumbs clinging to it - be careful not to overcook the brownies. Remove from the oven, then stand the tray on a wire rack until cool enough to cut into squares.