Melt the chopped unsweetened chocolate in a metal bowl over a pan of simmering water. Add 1 cup of the chocolate chips, and the butter stirring occasionally until the mixture is smooth. Remove from the heat and set the bowl aside to cool for about 10 minutes.
In a large bowl, whip eggs and sugar until thick and a pale color, about 2 minutes. Stir in the vanilla and the chocolate mixture until well mixed.
Combine the flour, cocoa, baking powder and salt. Gradually stir the chocolate mixture into the dry ingredients. Gently stir in the remaining 1 cup chocolate chips. Cover the cookie dough and chill for at least one hour or over night.
Preheat oven to 350 degrees F. Shape, with your fingers, dough into 1 inch balls. Place each ball on an ungreased cookie sheet or atop parchment paper, 2 inches apart. Bake for 9-11 minutes. Cool cookies for 5 minutes on the baking sheet, then remove with spatula and place on a wire rack to cool completely.