Step 1

Preheat the oven to 170°C. Grease and line the base of a 26cm springform cake pan. Place 2 layers of foil on the outside of the pan (this prevents water seeping into the pan while cooking in the water bath).

Step 2

Crush biscuits in a food processor. Combine butter with biscuit crumbs and press into the base of the pan. Refrigerate for 10 minutes.

Step 3

Place the cream and all the chocolate in a bowl over a pan of gently simmering water until it has melted. Set aside to cool slightly.

Step 4

Place the cream cheese, ricotta, caster sugar and vanilla extract in a food processor and process until smooth. Add the eggs yolks, one at a time, until combined. Add the chocolate mixture and process until just combined, then transfer to a large bowl.

Step 5

In a separate bowl, whisk the eggwhites until stiff peaks form, then carefully fold into the chocolate mixture. Pour over the biscuit base and smooth the top. Place in a roasting pan and pour boiling water into the roasting pan to come halfway up the sides of the springform pan. Bake in the oven for 1 1/2 hours. The cake will still have a slight wobble.

Step 6

Turn the oven off and leave in the oven for about 1 hour to cool, then refrigerate overnight.

Step 7

Serve the cheesecake garnished with some chocolate curls.