Start by taking the dividers out of your battenburg tin and lining the base with baking parchment. Replace the dividers and spray liberally with oil/bake release/brush with melted butter. This really helps getting it out after baking so don't skip it.

Preheat the oven to 180C.

Start by dissolving the food colouring gel in the boiled water - I do this in a tiny bowl or teacup with a tiny spatula. This makes it so much easier to blend into the batter later. Set aside.

Cream the butter and sugar very well then beat in the eggs, with a little of the flour to prevent curdling, followed by the peppermint extract. Fold the rest of the flour in.

Divide the batter in two (I am pedantic enough to weigh it and split evenly - this is easier if you know the weight of your mixing bowl before you start!). Into one half, fold in the watered down red food colouring and stop as soon as there are no more streaks. Fill your two piping bags with the plain and red batters.

Cut off a wide opening (about 2cm) from each bag and pipe exactly half into two of the "lanes" in the battenburg tin. It's soooo much easier than trying to spoon it in, it is very well worth getting some piping bags for this purpose.

Bake for 25-30 minutes until very well risen and a skewer comes out clean when inserted into the centre of each cake. The cake should rise above the level of the tin but not spill over if using these exact amounts.

Leave to cool on a baking rack until room temp then use a very sharp serrated knife to trim any excess off level with the tin - it is much easier to get a neat finish doing it this way than freehand after unmoulding the cakes.

Mix the buttercream up by beating the butter until light and fluffy then beating in the icing sugar and peppermint extract. Knead the marzipan or sugarpaste until soft then roll out to 8 by 12 inches approximately.

Now here comes the fiddly bit - sandwiching the strips of cake together with buttercream. I do this on a piece of reusable silicone but baking parchment would do too. Spread a thin layer of buttercream along the length of a red sponge, then offer up a white one to match it. Spread their tops with more buttercream then place a white strip on top of the red, and red on top of the white, again spreading a little buttercream in between them. Cover the outsides of the cake but not the ends with a thin layer of buttercream and if it is very soft, pop in the fridge for just 20 minutes before covering in marzipan.

Lay the rectangle of marzipan in front of you, long side facing you. Flip the buttercreamed cake into the centre of this marzipan, with it's short, non-buttercreamed edge facing you. It should match up sizewise pretty much perfectly and you will have two exposed sides of marzipan to wrap the cake up in once you've buttercreamed the base. Pressing the seam together neatly and trim off any excess.

Sit the cake on a serving plate with the seam side down and trim off the edges to expose the red and white checkerboard pattern. If not eating immediately, I press pieces of clingfilm up against the cut surfaces to prevent them drying out. It will keep for at most 2 days stored like this, preferably in a cake tin or other storage box.