Combine cream, coffee and peel in a saucepan, bring just to the boil over medium-high heat, strain over chocolate in a bowl and whisk until smooth. Cool, whisking occasionally so chocolate doesn’t separate from cream, to room temperature, then refrigerate overnight. The next day, whisk chocolate mixture until soft peaks form.
For meringues, preheat oven to 100C. Using an electric mixer, whisk eggwhites and a pinch of salt until soft peaks form. With motor running, gradually add caster sugar; whisk until glossy. Using a metal spoon, fold in icing sugar, hazelnut and cocoa. Trace 2 rectangles using a 20cm x 30cm cake pan as a template onto baking paper-lined oven trays. Spread meringue evenly onto rectangles, bake for 40 minutes or until crisp. Cool on trays.
For caramel, combine sugar, glucose and ¼ cup water in a small saucepan and stir over medium heat until sugar dissolves. Increase heat to medium-high and cook for 5-7 minutes or until dark caramel. Remove from heat, add ¼ cup water and espresso, swirl to combine. Add butter, swirl to incorporate, then cool.
Place a meringue rectangle, trimming edges to fit, into a 20cm x 30cm baking paper-lined cake pan. Drizzle with half the espresso caramel, top with chocolate mixture and drizzle with remaining espresso caramel. Top with remaining meringue and freeze overnight. Remove, cut into squares using a wet sharp knife and serve immediately.
Note Liquid glucose is available from the
baking section of supermarkets and health food stores.