Preheat oven to 375, and place rack in center of the oven. Fit muffin tin with 12 paper or silicon molds.

In a bowl over simmering water, melt HALF the chocolate and the butter. Remove from heat and set aside.

In a large bowl, whisk the flour, sugar, cocoa, baking powder, baking soda and salt.

In another bowl whisk the butter, egg, and vanilla until combined.

Add the chocolate/butter mixture and the egg/sugar mixture to the flour mixture and mix together. Do not over-mix.

Stir in remaining chocolate chips. Divide into muffin cups.

Bake about 20 minutes or until a toothpick comes out clean.

Cool for 5 minutes, and then eat while warm.