Preheat the oven to 350 and line a cupcake tin with liners.
Mix the dry ingredients together in a large bowl (flour, sugar, baking soda, baking powder, salt).
Combine the boiling water and instant coffee in a small bowl. In a sauce pan, melt the butter. Add the coffee mixture to the butter and let boil for about 10 seconds.
In a medium bowl, combine the buttermilk (or milk + vinegar), eggs, and vanilla. Slowly add the butter and coffee mixture to the medium bowl while continually whisking.
Add the wet ingredients to the dry ingredients and mix until combined. Pour into cupcake tins and bake for 20-25 minutes,