Preheat your oven to 170 Fan / 190 C / 375 F / Gas 5 and line a large baking tray with parchment
If you want to, draw round something on the underside of the parchment approx 2 inches (5cm) in diameter as a guide when piping your cookies. You can space these circles fairly close together as the cookies shouldn't spread
Cream together the vegan butter, icing sugar and vanilla extract until soft and fluffy. You can do this by hand, in a food processor or in a stand mixer using the paddle attachment
Beat in the flour and cornflour until well mixed but try not to overmix. If the dough feels too stiff to pipe add just a splash of boiling water in small increments until you have a pipeable dough
Spoon into a piping bag fitted with a star nozzle then pipe swirls of the dough onto your parchment until you've used all the dough - it should make roughly 20 cookies 4-5 cm (1 3/4 - 2 inches) in diameter
Bake for 20 minutes until lightly golden and just set
Leave to cool on the tray for 5 minutes then transfer to a wire rack to cool completely
Either while the cookies are baking or cooling make the buttercream by beating the ingredients together with 1 tblsp boiling water until very soft, pale and fluffy. Spoon into a clean piping bag with a star nozzle
Pipe the buttercream on the bottom (flat) side of half of the cookies then top with another cookie so the two flat sides are pressed against the buttercream
Store the cookies in an airtight container at room temparature
Recipe by The Cook & Him at https://thecookandhim.com/recipes/vanilla-sandwich-cookies/