Preheat your oven to 170C. Line a cupcake tray and set it aside.
In a bowl, add the milk and instant coffee, mix until the coffee dissolves (it helps if you use warm milk). Now add the oil, vanilla and vinegar, whisk really well. Set it aside.
In a separate bowl, sift the flour, cocoa powder, baking soda and salt. Add the sugar, whisk to combine.
Now make a well in the dry ingredients and pour the wet ingredients that we mixed earlier into it.
Mix gently, it is preferred if you just fold the ingredients with a spatula just until it is combined. You can also use a whisk to avoid lumps however, do not overmix your batter. Some small lumps are fine.
Using an ice-cream scoop portion this batter into your prepared cupcake tray and bake for 12-15 minutes. The baking time varies depending on the heat of your oven. You will know it is done when a toothpick inserted in the center of the cupcake comes out clean.
Let the cupcakes cook completely before frosting.
Add all ingredients for the frosting in a bowl and using an electric hand mixer, whip everything for 5-7 minutes or until the frosting is light and fluffy. Add more sifted icing sugar if you find that your frosting is stiff.
Optional: You can add 50 gram of melted (not hot) chocolate to the frosting to make it chocolate & peanut butter frosting. I also decorated mine with snickers candy.