1. Preheat the oven to 180°C. Cut a rectangle of non-stick baking parchment to fit the base and sides of a 30cm x 23cm x 4cm shallow tray or roasting tin. Grease the tin and then line it with the paper, pushing it neatly into the corners.
2. Measure all the ingredients into a large bowl and mix with until evenly blended (tip: if you have a hand-held electric mixer this works best!)
3. Spoon the mixture into the prepared tin, scraping the sides of the bowl with a plastic spatula to remove all of it. Spread the mixture gently to the corners of the tin and level the surface with the back of the spatula.
4. Bake for 40–45 minutes, until the brownies have a crusty top and a skewer inserted into the centre of the brownies comes out clean.
5. Cover loosely with tin foil for the last 10 minutes if the mixture is browning too much. Allow the brownies to cool in the tin and then cut into 24 equal squares.
6. Serve whilst warm or to store, ensure they are kept in an airtight tin