Mix together the flour, baking powder and salt; set aside.
In a metal bowl set over a saucepan of barely simmering water, melt chocolate with butter. Cool slightly (about 3 minutes). If you melt the chocolate over barely simmering water, it shouldn’t be too hot in the first place.
Beat eggs and sugar in a mixing bowl using high speed of an electric mixer for 2-3 minutes. Beat the melted chocolate mixture into the egg mixture. Beat in the vanilla. Add the flour mixture and stir it gently into the batter. Make sure the batter is cool, then add the chocolate chips and walnuts.
Chill dough for at least one hour.
Preheat oven to 375 degrees F. Line two cookie sheets with parchment paper. I used an insulated cookie sheet.
Scoop up rounded tablespoons of dough and set dough balls on parchment paper spacing about 2 ½ inches apart. Bake for 11-13 minutes. Let cookies cool on sheet for about 3 minutes, then transfer to a wire rack to cool.
Note sure of yield, but I'll estimate 20.