Sift the flour, baking powder and salt together. Set aside.

Melt the unsweetened and bittersweet chocolates together with the butter in a baine marie.

Whisk the eggs and sugar on high until they are very thick and are at a ribbon stage. Use a standard table top mixer.

Turn the mixer to a low setting and pour the chocolate mixture into the eggs.

Add the dry ingredients just until they are incorporated. Switch to a paddle attachment and add the walnuts and the chocolate chips.

Let the dough rest until it is firm. Scoop the cookies with a small ice cream scoop. Dip the scoop in hot water after each cookie is formed.

Bake at 325F for 6 minutes. Turn the sheetpan and bake for another 5 minutes.