Toast the walnuts and pecans using your favorite method. I usually lay them on a baking sheet and just heat at 350 until they are aromatic. Let cool, then chop.

While nuts are toasting, combine the butter and both chocolates in a microwave-safe bowl. Heat at 50% power, stirring every 30 seconds, until chocolate is melted and smooth. Alternatively, use a double boiler or saucepan set over low heat, but be sure to keep the heat low and gentle.

While the nuts and melted chocolate cool, thoroughly mix together the flour, baking powder and salt together in a small bowl; set aside.

In the bowl of a stand mixer fitted with the whisk attachment, beat the eggs for about two minutes. Very gradually add the superfine sugar to the eggs and continue whipping until thick and pale yellow. This should take about 5 minutes. Beat in the vanilla.

Switch the mixer attachment to the paddle or just remove the bowl from the stand and do the next step by hand. I do the rest by hand using a heavy duty scraper.

Stir the cooled melted chocolate (make sure it’s cooled or the batter will be too loose) mixture into the egg mixture until fully blended. Fold in the flour mixture, then stir in all the chocolate chips and nuts. Mixture should be thick enough to hold loose scoops. If it’s not thick enough to stay in heaps, something went wrong and you’ll need to ether let it stand for a few minute or, if it is totally loose, chill it. But this shouldn’t happen if you let the chocolate cool as directed.

Using a generous ¼ cup measure (or a 2 ounce ice cream scoop if you have one), scoop up chocolate batter and arrange on parchment or foil lined plates or sheets that fit in the freezer. Put the scoops of batter, covered with some plastic wrap, in the freezer and freeze for at least two hours or until ready to bake.

Preheat oven to 350F. Line two baking sheets with parchment paper or Silpats. Arrange 6 frozen chocolate balls on the sheet, spacing evenly and at least 3 inches apart. Bake for 18 to 20 minutes or until the cookies have developed a nice chocolate shell. Remove from the oven and let cool on the baking sheet or until they are set enough so that you can lift them without breaking. Carefully transfer to a wire rack and let cool completely (or cheat and throw them in the refrigerator).