Nana’s coffee and walnut slice

This is my favourite nana recipe. It’s been part of my life for as long as I can remember. My husband nicknamed it Nana’s heroin slice because of its addictiveness. On arriving home every year there would be tins of the stuff to go with endless cups of tea we had with her. She made us a double batch once for a climbing trip in the Southern Alps. It fuelled our whole trip and I’m amazed we weren't diabetic by the time we returned.

Make this gluten or wheat free by using appropriate biscuits.

This keeps for seven days in the fridge.

generous slices

For the base

175g butter

250g condensed milk

11⁄2 Tbsp instant coffee granules

250g rich tea biscuits

100g walnut halves, roughly chopped,

plus a handful for the top

90g desiccated coconut, plus a handful

for the top

For the topping

1 Tbsp instant coffee granules

1 Tbsp boiling water

170g cream cheese

60g butter, melted

370g icing sugar

30cm x 23cm brownie tin

Method

Grease and line the tin with greaseproof paper.

Melt the butter, condensed milk and coffee granules together in a saucepan over a low heat, using a whisk to make sure all the coffee granules dissolve. Put the biscuits in a large mixing bowl and smash with the end of a rolling pin until you have small pieces they want to be small chunks, not fine crumbs. Add your walnuts and desiccated coconut, then pour over the hot condensed milk and stir thoroughly. Scrape out into your lined tin and press down to make a wellpacked base. Leave aside while you make your topping.

Put the instant coffee in a small bowl, then add the boiling water and stir till the granules have dissolved. Put your cream cheese, melted butter and icing sugar in a mixing bowl and add the coffee. Beat until everything is combined to make a smooth, glossy and fluffy icing. Spoon this over the biscuit base and smooth out with a spatula, then sprinkle with walnut pieces and some desiccated coconut as a garnish. Leave to set in the fridge for a couple of hours before cutting into 16 slices.