Preheat oven to 185°C/165°C fan-forced. Grease a 22cm springform pan and line base with baking paper.

Place biscuits, sugar and zest in a food processor and whiz until a powder. Add melted butter and whiz until combined. Spoon into prepared pan and press into base and up the sides, packing down to ensure a smooth, even layer. Bake for 10 minutes, then set aside until cool. Reduce oven to 160°C/140°C fan-forced.

For the filling, whiz sugar and lemon zest in a clean food processor. Add the cream cheese and whiz until smooth. Add lemon juice, sour cream and vanilla and whiz until fully combined. On medium speed, add eggs one at a time, and whiz until just blended. Sift over the flour and pulse to incorporate, taking care not to overmix. Pour mixture into the prepared pan and smooth top. Place pan in a 24cm round cake pan.

Place larger pan in a deep baking tray and place in oven. Pour enough boiling water into baking tray so it comes halfway up the side of cake pan. Bake for 1 hour 15 minutes, or until cheesecake is set but still has a slight wobble in the centre (it will continue to bake as it cools).

Carefully remove baking tray from oven and leave cheesecake in the water bath for 30 minutes. Transfer springform pan to the fridge and chill for at least 4-6 hours. or overnight, before removing cake from pan to serve.

Meanwhile, for the limoncello caramel, place the lemon juice in a small saucepan over medium heat, bring to the boil and boil until reduced to ¼ cup (60ml). Set aside. Place the sugar in a medium saucepan over medium heat. As the sugar melts, occasionally swirl the pan until a dark golden caramel. Slowly add the lemon reduction, taking care as the caramel will spit. Whisk and return to the boil to ensure sugar is completely dissolved. Set aside for 10 minutes to cool slightly. Slowly whisk in the butter, a few pieces at a time. Cool to room temperature. Add the limoncello to taste and stir to combine. Set aside.

Close to serving, make the meringue. Transfer cheesecake to a serving plate. Place all meringue ingredients and a generous pinch of fine salt in a large heatproof bowl set over a saucepan of simmering water (don’t let base of bowl touch the water). Whisk until mixture becomes white, doubled in volume and hot to touch (you shouldn’t feel any grains of sugar between your fingers). Transfer to a stand mixer fitted with the whisk attachment and whisk on medium speed for 5 minutes until glossy, smooth and stiff. Spread immediately onto cheesecake. Torch with a kitchen blowtorch until golden.

Decorate with dehydrated lemons and serve with limoncello caramel alongside.