To make the biscuit dough, beat together the vegan butter and caster sugar in the bowl of a stand mixer for around 2 to 3 minutes until pale and fluffy. Add the vanilla paste and flour, then slowly beat to combine to a soft dough. Wrap the dough in cling film and chill for 30 to 45 minutes.
Preheat the oven to 200oc/180oc fan and line two baking sheets with greaseproof paper. On a clean, lightly floured work surface, roll the dough to the thickness of a pound coin. Using a 4cm round cutter, cut out as many biscuit shapes as you can, rerolling the scraps until all the dough has been used up.
Arrange the biscuits on the baking trays then place in the oven to bake for 10 to 12 minutes until lightly golden around the edges. Cool on the trays for five minutes then transfer to a wire rack to cool completely.
Once the biscuits are cold, match up the biscuits then place a dollop of jam on the underside of one biscuit and top with another the right side up. Repeat with the remaining biscuits until the jam has been used up.
To decorate, mix together the icing sugar and the boiling water to a smooth yet slightly thick icing. Dollop onto the top of each empire biscuit and smooth to the edges with the back of a spoon. Top with a jelly tot then leave the biscuits to set. Store in an airtight container for up to five days.
Recipe by Victoria Sponge Pease Pudding at http://victoriaspongepeasepudding.com/vegan/vegan-empire-biscuits/