Recipe: Make our indulgent Espresso walnut, rum and chocolate slices

They say you should never mess with a classic – but Charlotte disagrees.

'Why on earth would you want to do that?' my colleague Nick looked aghast at me over the desk last week after I'd told him about my 'mad' baking idea.

Sometimes the best results come from our experiments. Let's face it, if no one had moved on and played about with the plain sponge, the world of cake (and afternoon tea) would be exceedingly dull wouldn't it?

My inspiration began with a friend Nicola offering (read – frantically tried to offload) a bumper crop of walnuts from her garden to me. I never say no to home grown produce and as I filled up a bag in her greenhouse, admiring layers of windfallen apples stacked in crates, I felt a massive pang of jealously.

'I want a walnut tree,' I told my husband when I got home, hiding the walnuts from the squirrels (kids). 'And a plum tree…oh and a peach tree too.'

'No,' was the flat out answer. Apparently he's worried the roots will creep under our house and tip it over. He must know by now I'm going to ignore him and buy them anyway. I spotted a dwarf growing walnut tree online and have already in my mind spied the perfect place for it in our garden – away from the house of course. It promises nuts within two to three years, meaning I could make as many batches of this lovely new invention of mine as I like.

Coffee and walnut is by far my favourite cake (when done well). But I also love at this time of year to occasionally make the Hungarian zserbo slice – layers of shortbread filled with sweet crushed walnuts and apricot jam, covered in dark chocolate. And Nanaimo bars, smooshed inside with a thick vanilla custard, also float my boat. Sitting at the kitchen hatch with my baking cogs whirring I created a monster – albeit a rather good one. Eating it one of my friends almost had a 'When Harry Met Sally' moment, and I had to keep moving the tin away from my husband, who managed to single-handedly devour half of it.

So. You've got a thick, short, crumbly biscuitty base, heady with espresso coffee grinds. On top is a coffee and rum buttercream custard icing flecked with tiny pieces of fresh walnut. There's a layer of dark chocolate. And, the crowning glory, a golden, crunchy walnut praline. Served in small squares with a cup of something warm, it'll (almost) make you feel like you're sitting in a Viennese coffee house.

The key to this bake is super fresh walnuts. If you can get your hands on some from a farm shop or grocer that's great. Otherwise, if you're using pre-packaged, shelled nuts, give a few a taste before cooking to test they haven't turned bitter.

Get in touch and tell me how you got on at charlotte.smith-jarvis@archant.co.uk You'll also be able to find this recipes and others on the Eat Suffolk and Eat Norfolk Facebook pages. Share with your baking buddies.

Espresso walnut, rum and chocolate slices

(makes a 27cm x 20cm bake serving 12-20 depending how you cut it)

Ingredients

For the base:

225g unsalted butter, cubed

100g rice flour

225g plain flour

Pinch salt

100g caster sugar

2tbsps fine espresso grinds (not instant)

For the filling:

100g unsalted butter

Pinch salt

3tbsps rum mixed with 2tbsps very strong coffee

4tbsps custard powder

250g icing sugar, sifted well

100g walnuts, crushed into very small pieces

Top top:

150g dark chocolate

1tbsp unsalted butter

100g caster sugar

100ml water

150g walnuts, crushed into rough pieces

Salt to finish - I used smoked Maldon salt

Method

Set the oven to 180C and line a 27cm by 20cm brownie or roasting tin.

Pop the butter, flours, sugar, salt and espresso powder for the base into a food processor and blitz to breadcrumbs. Add icy chilled water, spoon by spoon, until it comes together into a dough.

Press evenly into the prepared tin and chill for 20 minutes. Now pop into the oven to bake for 15-20 minutes until golden around the outside.

Place on a rack to cool, then turn out.

Blend together all the filling ingredients, adding the coffee, rum mix until you have a creamy, spreadable icing. Spread evenly over the base and pop the whole thing in the fridge to set for 30 minutes.

In the meantime, place the sugar for the topping in a small pan with the water. Simmer to dissolve, then crank the heat up until it turns caramel in colour. Add the walnuts, stir, and pour onto a piece of greaseproof paper on a plate. Leave to set. Once cool and set, place in a bag and bash with a rolling pin to break into pieces.

Melt the chocolate in a bowl over a pan of simmering water with the butter. Spread over the chilled base, then sprinkle over the candied walnuts and a tiny pinch all over of flaky sea salt. Cut into pieces and serve.