I used Horlicks powder as thats what I had in my cupboard – most malt powders (which need milk added to them) will work fine such as Ovaltine!
If you want an extra chocolatey fix, you can add in 100g of chocolate chips to the cupcake mix!
If you are loosening the cupcake mixture or the buttercream with milk, it's important to use whole milk because of the fat content, using semi-skimmed might make it split.
These cupcakes will last in an airtight container for 3 days at room temperature!