Put the biscuits into a large bowl and crush into crumbs using the end of a rolling pin, then mix in the melted butter until thoroughly combined. Pour into a 20cm diameter loose bottomed cake tin and push down so you have a tightly packed, level layer covering the bottom of the cake tin. Put in the fridge whilst you start on the vanilla layer.
In a bowl, add 300g of the cream cheese and mix with a whisk until the cream cheese has loosened to a smooth consistency. Add the vanilla extract and 100g of the icing sugar then whisk again until combined. Take about 4 or 5 strawberries and chop into chunks, then add them to the mixture and stir in gently. Take the biscuit base out of the fridge and spread this vanilla layer on top. Put back in the fridge.
Next make the mousse layer. Chop the jelly into chunks and mix with 100ml of boiling water until dissolved. If the chunks aren't dissolving well, then put it in the microwave for 30 seconds or so and mix again. Set aside to cool slightly. Add the remaining 200g of cream cheese to a large bowl and mix using the whisk until it's smooth. Whisk in the remaining icing sugar, then whisk in the evaporated milk. Finally add the jelly mixture and whisk in. Pour this mixture onto the top of the cheesecake and put back in the fridge to set for at least an hour.
Once the mousse layer has set (check by giving it a prod), you can decorate with the strawberries. Take the cheesecake out of the fridge and carefully slide out of the cake tin and onto a plate. Slice the strawberries into thin slices (you may need to discard - ok, erm scoff- the smaller end slices). Arrange the strawberries in a circle around the cheesecake, starting from the outside and working your way in. Overlay the strawberries slightly so you're not left with any gaps. Sprinkle the top with the orange zest and serve.
***Tip*** Store in the fridge with a covering of tin foil until it's time to serve. This should keep in the fridge for a couple of days..Nutritional Information is per serving ( based on getting 8 servings from the recipe).