Traditionally made with oats, muesli-style bars also taste great with buckwheat flakes instead, readily available in the health food shop, and they are gluten- and wheat-free too.
Preheat the oven to 180°C/350°F/Gas 4. Cut a piece of baking parchment a little larger than an 18 x 28 x 4cm/7 x 11 x 1½in rectangular tin or pan, snip into the corners then press the paper into the tin so that the base and sides are lined.