To make the base
Crush the biscuits into crumbs (e.g. in a food processor). Melt the margarine in a saucepan, add the biscuit crumbs and sunflower seeds, mix well and then press this mixture into the bottom and side of a round flan dish. Chill in the fridge.
To make the filling
Blend all the ingredients together with a small amount of soya milk, and then keep adding the soya milk until you get a thick, creamy consistency. Blend thoroughly. Then taste the mixture – depending on the tartness of the berries – you may need to add more sugar at this stage (or maple syrup, if you prefer). Once you’re satisfied with the sweetness, pour the mixture onto the biscuit crumb base.
Bake the cheesecake at 200°C/400°F/gas mark 6 in the middle of a preheated oven, for 25-30 minutes. Then leave to cool, and chill thoroughly in the fridge, before decorating (with berries) and serving with vegan vanilla ice-cream, or cream, plus an optional dash of maple syrup.