Preheat oven to 200°C/ 400°F and prepare 12 cupcake cases on a tray.
Mix together the plant-based milk and vinegar and set it aside for 5 minutes.
In a large bowl, mix together the flour, baking powder and sugar.
Add the milk mixture, the oil and the vanilla extract. Mix well until you have a smooth cake batter.
Divide the batter between the cases and bake for around 15-20 minutes until golden brown on top.
While the cakes are baking, prepare the topping by mixing together the vegan butter and powdered sugar with a wooden spoon. Add the vanilla extract and mix again. If it's too thick, you can add a splash of plant-based milk and if it's too thin, you can add more powdered sugar.
Stir in the food coloring then spoon the frosting into a piping bag.
Top each cupcake with a Party Ring biscuit.