Preheat oven to 180*C/350°F (160°C fan-forced). Grease and line the base only of a 23cm / 9" tart tin with a loose base. (Or a springform pan of a similar size)

Blitz biscuits - Roughly break up biscuits and place in a food processor, then whizz until fine crumbs form. Or do this step with a ziplock bag and rolling pin.

Press - Pour crumbs into a bowl, add melted butter, mix until it looks like wet sand and no dry crumbs remain. Pour into tin, then press firmly into base and sides – use something flat like a cup to assist (refer to video).

Bake & cool - Transfer to tray (safe handling), place in oven and bake for 10 minutes, then remove and cool slightly (5 minutes in fridge).

Melt butter in a large saucepan over medium heat. Add sugar and whisk to combine – butter may not incorporate fully.

Whisk - Once it starts bubbling and the sugar is completely melted, pour in the condensed milk, whisking as you go. Whisk constantly until you see steam coming off the caramel (~ 4 minutes), then remove from heat.

Pour into base - Add salt (adjust to taste), then pour the caramel into the tart base.

Bake for 15 minutes or until the edges of the caramel surface is golden and the surface has a “skin” on it, but the caramel is still soft and the centre jiggles slightly (see video for demo.)

Cool on counter while you make the chocolate.

Melt chocolate - Place cream and chocolate in a heat proof bowl. Microwave in 2 x 30 second bursts, stirring in between, until smooth.

Cool then pour - Set aside for 10 minutes to thicken slightly, then pour over the base. Smooth top or make swirls like I did (just wait until the chocolate thickens slightly). Sprinkle with sea salt flakes.

Refrigerate for 1 1/2 hours to allow chocolate to set. Then remove and bring to room temperature before slicing to serve. Handle carefully when sliding the tart off the base - or just leave it on to be safe and just remove the sides.