1. Preheat the oven at 350 degrees F.
2. In a bowl sift the dry ingredients together.
3. Beat together condensed milk and butter with an electric hand blender.
4. Add vanilla extract and vinegar and beat.
5. Add milk little by little at a time and blend.
6. Add the dry ingredients into the wet ingredients little by little and blend with the blender to form a smooth batter.
7. Fill the cupcake maker with the batter using a 1/4 cup measurement.
8. Top each cupcake with 1 1/2 tablespoon of nutella.
9. In the nutella cups slowly stir the cake batter and frosting with the help of a toothpick.
10. Place in the preheated oven preferably on the middle rack and bake for about 20 minutes.
11. Check for doneness by pricking the center of the cake with a toothpick.