Line an 8x8" tin with baking paper.
Add the vegan butter, white chocolate and Biscoff Spread to a large, heat proof bowl and either melt in the microwave (in 30 second bursts, stirring in between), or place over a pan of simmering water (not letting the bowl touch the water) and melt until smooth.
Remove the bowl from the heat and stir in the marshmallows and broken biscuits and stir until thoroughly combined.
Pour this into the lined tin and flatten down - I find it easier to do this by placing a piece of baking paper over the top and gently pressing down until flattened.
Place in the freezer to set for 30 minutes - 1 hour. Remove and drizzle over some melted Biscoff Spread (I microwave it for a few seconds until runny), let the drizzle set before slicing into 12 slabs. Store in an airtight container in the fridge.
