Preheat the oven to 350 degrees F. Line cookie sheets with parchment paper.
Sift the flour, baking powder and salt into a bowl and set aside.
Melt the unsweetened chocolate, chopped bittersweet chocolate and the butter in a double boiler over low heat, stirring constantly.
With a hand mixer beat together the eggs, sugar and vanilla on medium-high speed until light in texture and thick, 3 to 4 minutes.
Add the chocolate mixture and blend thoroughly.
Turn the mixer on low speed, mix in the dry ingredients until just combined. Mix in the pecans and chocolate chips until blended.
Fill a 1/4 cup ice cream scoop with dough, level it, and drop the dough onto a prepared cookie sheet, leaving 3 inches between the cookies.
Bake the cookies until they are cracked on top, about 14 minutes. Cool on wire racks