Biscoff & miso chocolate silk tart

For the base, melt together 40g butter plus 25g dark chocolate and 25g milk chocolate in a heatproof bowl over a pan of simmering water; stir to combine. Meanwhile, crush the bourbon biscuits to fine crumbs – either bash with a rolling pin or whizz them in a food processor – and put in a bowl. Once the chocolate mixture has melted, pour it over the biscuit crumbs and stir until well combined.

Tip the mixture into a 20cm fluted tart tin and press into the base and sides as evenly as possible. Chill, covered, for 20 minutes.

Spread the Biscoff onto the cooled biscuit shell, then cover and return to the fridge while you make the chocolate topping.

Melt 125g of roughly chopped dark chocolate and 125g of roughly chopped milk chocolate with 50g unsalted butter and miso in a large heatproof bowl set over a pan of simmering water. Once melted, remove from the heat and set aside. In another large heatproof bowl, whisk the eggs and sugar over a pan of simmering water. Don’t stop whisking as the bowl heats up or the eggs will coagulate and you’ll need to start again.

Once the egg mixture is loose and feels hot to the touch (about 5 minutes), pour it into the melted chocolate mixture and whisk to a smooth, silky ganache. Pour the filling into the tart case, then chill until set (about 2 hours).

The tart looks impressive as it is, but if you want to decorate it, melt about 75g milk chocolate in a bowl over a pan of simmering water, then use a spoon to drizzle it around the edge of the tart. Scatter over some crumbled bourbon biscuits, if liked. If you’re going all-out, sprinkle over some toasted chopped hazelnuts too and spray with a little gold lustre spray.