Grease a loose bottom cake tin with vegan spread.
Blend the digestives until fine or put in a clean tea towel and bash with a rolling pin until smooth.
Gently melt the margarine in a small saucepan on a low heat until fully dissolved. Combine thoroughly with the blended digestives in a large mixing bowl.
Empty the mixture into the greased cake tin and evenly distribute along the bottom, packing firmly with the back of a spoon or with your hands. Place in the fridge until you need it.