Heat oven to 350 degrees Fahrenheit/180 degrees Celsius.
Line a cupcake tin with paper liners or heavily grease and flour the tins.
Mix milk and vinegar in a cup and set aside.
Put sugar in a large bowl. Sift flour, cocoa, baking powder, baking soda and salt into the bowl. Mix well. With the mixer on, add 2 eggs, milk with vinegar, oil and vanilla. Mix until smooth.
Slowly add boiling water and mix until smooth.
Pour batter into a measuring cup or bowl with spout for easier pouring. Fill cupcake liners only halfway as they will rise. Bake in oven for 20 minutes or longer depending on your oven. Check by inserting toothpick into center of cupcake. If toothpick comes out clean or with few crumbs, cupcakes are cooked.
Completely cool cupcakes on a rack before removing paper liners or frosting. The cupcakes are extremely moist and full of chocolate flavor. I like to frost these with a simple whipped cream frosting.