1 1/2 c. finely chopped nuts (walnuts)
12 oz. bag semi-sweet chocolate chips
3/4 c. butter (unsalted best)
3 tbsp. unsweetened cocoa powder
1/3 c. sugar
4 egg yolks
5 egg whites
Pinch of salt

Generously butter bottom and sides of 1 quart loaf pan. Line bottom with parchment or foil; butter and sprinkle 1 cup walnuts over bottom and up sides of pan, press into place.

Combine chocolate, butter, cocoa in 1 quart pan and cook over low heat, stirring occasionally until chocolate and butter are melted. Remove from heat. Set pan in bowl of ice water to cool (do not let harden). Transfer mixture to large bowl. Add sugar and beat at medium speed until well mixed. Beat in yolks - 1 at a time. Set aside.

Beat whites and salt in another bowl until stiff and glossy. Stir 1/4 of whites into chocolate until well-blended, then gently fold in remaining whites. Turn into loaf pan. Cover with plastic wrap. Refrigerate until well chilled.

Carefully separate mousse from pan with knife or spatula. Invert. Press remaining nuts into mousse to cover bare spots. May be made 1 month ahead, wrap airtight and FREEZE. Thaw in refrigerator 24 hours before serving.