1. Add semisweet chcolate chips and 2 tbsp. of melted butter to a saucepan over medium-low heat. Melt the chocolate and the butter together , stirring frequently until smooth and completely melted. Remove from heat and let it cool about 5 minutes.
2. In a mixing bowl combine flour, baking powder and salt. Stir and set it aside.
3. Beat butter and sugar in large mixing bowl until smooth and creamy. Beat in eggs, one at a time, beating well after each addition. Beat in vanilla extract.
Add the flour mixture in a butter mixture and continue beating until well combine.
4. Remove part of the batter and place to a separated bowl, Add the cocoa powder, stir in melted chcolate.Add the grated milk
chocolate and mix well. Using a spoon divide the batter into your prepared cupcakes cups (1tbsp. of every batter). Using toothpick or knife, gently draw swirls through the batter to marbleize.
5. Bake for about 18-25 minutes in a preheated oven (175degree C) or until a toothpick inserted in the center comes out clean. Remove from oven and let it completely cool before serving.
