Coffee Cloud Cake
["2 Tbsp. instant coffee granules, divided", "1 c. boiling water", "2 c. all-purpose flour", "1 Tbsp. baking powder", "1/2 tsp. salt", "6 large eggs, separated", "2 c. sugar, divided", "1 tsp. vanilla extract", "2 1/2 c. chopped walnuts, divided", "1/2 tsp. cream of tartar", "1/4 c. milk", "1 (16 oz.) pkg. powdered sugar, sifted", "1/4 c. plus 2 Tbsp. butter or margarine, softened"]
["Dissolve 1 tablespoon granules in boiling water.", "Set aside. Combine flour, baking powder and salt; set aside.", "Beat egg yolks in a large mixing bowl until thick and pale.", "Gradually add 1 1/2 cups sugar; beat until blended.", "Beat an additional 5 minutes at high speed.", "Add reserved flour mixture to egg yolk mixture, alternately with reserved coffee mixture, beginning and ending with flour mixture.", "Mix after each addition.", "Stir in vanilla and 1 cup walnuts.", "Beat egg whites and cream of tartar at high speed of an electric mixer until foamy.", "Gradually add remaining 1/2 cup sugar, 1 tablespoon at a time, beating until stiff peaks form and sugar is dissolved (2 to 4 minutes).", "Fold one-fourth of egg white mixture into egg yolk mixture; carefully fold in remaining egg white mixture.", "Pour batter into an ungreased 10-inch tube pan. Bake at 350\u00b0 for 60 to 70 minutes or until cake springs back when lightly touched.", "Invert pan, using a narrow metal spatula; remove from pan.", "Place on a serving plate."]
["coffee granules", "boiling water", "flour", "baking powder", "salt", "eggs", "sugar", "vanilla extract", "walnuts", "cream of tartar", "milk", "powdered sugar", "butter"]