Using a food processor or rolling pin crush the biscuits to a fine powder. Melt the margarine and stir in the crushed biscuits. Mix together well, then pour mixture into a 20cm loose bottom cake tin and press until surface is even.
Beat the cheese until smooth and then mix in the eggs and sugar. Melt the chocolate slowly in a bowl over a pot of boiling water (or in the microwave) and let cool slightly.
Stir the chopped strawberries, raspberries and melted chocolate into cheese. Spoon mixture on top of biscuit base and smooth out.
Put in the oven for 1 hour then turn off the oven and leave the cheesecake to cool with door open. When it is completely cool transfer to a plate and enjoy.
To reduce the calorie and fat content I use light mascarpone and light biscuits. Makes you feel a little less guilty and lets you indulge!