Easy Christmas Cheesecake Slab

Step 1: Lightly grease a 23 x 33 cm / 9 x 13-inch pan with butter or plain oil spray, just enough for the paper to stick. Line it with baking paper, leaving plenty of overhang along the long sides so you can lift out the cheesecake once it has set.

Step 2: Break the biscuits up roughly by hand and put them in a food processor. Blitz until they become fine crumbs, about 30 seconds.

Step 3: Add the butter, cinnamon and salt. Blitz until the mixture resembles wet sand, about 10 seconds. It should hold together when pinched between your fingers.

Step 4: Pour the crumbs into the prepared pan. Spread them out and press firmly with your hand or something flat; a firmer crust makes a more stable base. Refrigerate until needed.

Step 5: Put the water in a small bowl and sprinkle the gelatin across the surface; do not dump it in one place. Whisk until dissolved, then set aside for 3 minutes or until it firms up like rubber.

Step 6: Microwave on high for 15 seconds or until the gelatin melts; do not let it boil. Let it cool for 5 minutes while you make the filling, and use it while it is still liquid. If a skin forms on the surface or sides, warm it for 5 seconds to liquefy it.

Step 7: Put the cream in a bowl and whip with an electric beater on high for 2 1/2 to 3 minutes, until firm peaks form. Do not stop at soft peaks; the cream needs good aeration.

Step 8: Put the cream cheese and sugar in a separate large bowl. Using the same beater without cleaning it, beat on high for 1 1/2 minutes, just until soft and smooth. Add the vanilla, lemon and melted gelatin, then beat on high for 10 seconds to mix thoroughly. Do not beat excessively, or too many air bubbles may form.

Step 9: Add about 1/4 of the whipped cream to the cream cheese mixture. Gently fold it in with a rubber spatula or large spoon so you do not knock the air out of the cream. Then fold in the remaining cream.

Step 10: Pour the filling into the pan and smooth the surface. Cover the pan with a large cutting tray, baking tray or foil; do not use cling wrap, which may sag onto the surface. Refrigerate for 12 hours or longer, until set.

Step 11: Use the paper overhang to lift the cheesecake out of the pan and transfer it to a serving platter. Slide the paper out from underneath, then refrigerate until ready to decorate.

Step 12: Put the whipped cream ingredients in a bowl and whip on high for 2 to 3 minutes, until softly whipped. Use an electric beater or a stand mixer fitted with a whisk.

Step 13: Spread the cream in big swirls across the cheesecake. Pile on the berries and cherries, tuck in the orange slices and rosemary, and dust with icing sugar. Cut into slices and serve.