Melt the butter, sugar and treacle together in a small pan over a gentle heat. Leave to cool.
Add the vinegar to the milk and leave for about 10 minutes until curdled.
Sift the flour, spices, salt, baking powder and bicarbonate of soda together into a large bowl.
Once the butter mixture has cooled pour it and the milk mixture into the dry ingredients, stir together until combined.
Pour into the prepared cake cases. You should have enough for about 24 muffins.
Bake in the preheated oven for about 20 minutes until risen and springy to the touch.
Leave to cool completely before decorating.
Notes
Nutritional information doesn't include optional buttercream - check out my vegan buttercream recipe for ingredients and nutritional information. If you want to make lemon buttercream add 1 tsp lemon juice and the grated rind of one lemon to the buttercream mixture.Nutritional information is only an approximate guideline. Calculations will vary according to the ingredients you use and your cooking methods.