These biscuits pull on my heartstrings as they remind me of the boiled sweets that I used to have as a child. So when I came across this recipe in Yotam Ottolenghi’s book Sweet I simply had to try. The biscuit (it’s a pimped up version of my Viennese Whirl recipe) contains custard powder and this not only gives a great taste but the yellow peps contrasts nicely with the pink of the fruit.
Note for my American followers in this blog I mean Biscuits as in the UK version not the ones you serve with gravy! Boiled sweets are hard candy.
Rhubarb is not generally available in the UK yet, although we are just coming into the ‘forced’ season. You need only one stick of rhubarb, so go for a nice pink one. I upped the level of lemon juice in my butter cream mix as I thought it brought out the rhubarbness – however the recipe below follows the one in the book.
I always use Birds custard powder; I am not a fan of some of the own brand ones. In the USA there is some debate as to how close your version is to our original one, but go for the best one you can get.
Chop up your rhubarb into 3cm sticks and pop them onto a baking tray (lined with baking parchment - I forgot mine and had to scrape!). Bake in oven set at 180C/160C Fan/Gas 4/350F for 20 to 30 mins. Keep an eye as they can burn. When baked allow to cool and whiz up in a small food processor. There is not much of it but it should be a strong taste.
Whiz in the 65g of cubed butter until combined. I then transferred this to a mixing jug.
Whip in the icing sugar and lemon juice keep going until the mix is smooth a light pink. Put this mix aside, if it is a hot day pop it in the fridge, you'll need a spreading constancy. Too soft and it will just ooze out and too firm and it will not spread easily.
Then move on to making the dough
Sift the flour, custard powder, icing sugar and salt into your mixer bowl and mix well. Drop in the cubed butter and mix. The original recipe says whisk for 30 seconds until the dough comes together. My kitchen was a little cold so I needed to push the dough together with my hands, but whatever you do you should not overwork it.
Take pieces off the lump of dough and roll them into a ball - about the size of an egg yolk. On a lined baking tray (you’ll need two trays) space the balls 4cm apart. Dip a fork into plain flour to stop it sticking and press the prongs into the surface of the ball to squash it flat(ish) and to mark with stripes that will remain when the cookies are baked.
Bake in an oven set at 170C/150C Fan/Gas 3/325 F. Bake for 25mins but keep an eye on them you hardly want them to colour. When roughly half way through cooking turn the tray around to ensure even cooking. Once cooked take the trays out of the oven but do not touch the cookies until they have rested for 5 mins, if you touch them too soon they will just break apart. Once cooler transfer to a wire rack to get totally cold.
Finally generously spread the bottom of one biscuit and sandwich a second one onto the butter cream. It does look like quite a bit of buttercream but trust me they are wroth every calorie! Serve with lots of tea - de-lish!