Pre heat the oven to 200°/ 180° fan / gas 5. Line a muffin tin with 10 muffin cases. Place an oreo biscuit into each of the cases.
Make the buttermilk by adding the lemon juice to the oat milk and then set to one side
In a stand mixer, sieve the flour, baking powder, bicarbonate of soda and cocoa powder. Add the caster sugar and combine the ingredients.
In a bowl whisk the sunflower oil, vanilla and buttermilk.
Make a well in the centre of the dry ingredients and pour in the wet ingredients. Mix for 1 minute on a low/medium setting until no flour is visible. Scrape down the sides of the mixing bowl then pour the mixture into the muffin cases, filling just up to half way. These cupcakes rise really well so don’t be tempted to overfill!
Bake at 200°/ 180° fan for 18-20 minutes. Insert a skewer and check to see it comes away clean. Allow the cupcakes to cool completely before icing.
Prepare the cream cheese frosting by whisking the vegan butter and the vegan cream cheese on high for 3 minutes. Then with the stand mixer on low/medium, add the sifted icing sugar in thirds, mixing for a minute in between each addition. Once well mixed and smooth, add the cornflour and lemon juice and mix for a further minute. Add the mixture to a piping bag. Pipe the frosting over each cupcake in a spiral motion, starting from the edge and working your way inwards.
Crush 3 oreos into crumbs and sprinkle over the cupcakes. To finish, cut 5 oreos in half and top each cupcake with half an oreo.