Preheat oven to 425F. and butter and flour an 8-inch round cake pan, knocking out excess flour.

In a small saucepan melt butter over moderate heat and cool. Stir in vanilla. In a food processor blend together nuts, brown sugar, and flour until nuts are ground fine.

In a bowl with an electric mixer beat whites with salt until they hold stiff peaks and fold in nut mixture gently but thoroughly. Fold in butter mixture (batter will deflate) and spread batter in prepared pan.

Arrange plum slices evenly over batter and sprinkle with granulated sugar. Bake cake in middle of oven 20 to 25 minutes, or until a tester comes out clean. Turn cake out onto rack and cool, plum side up, 5 minutes.

Sift confectioner's sugar onto cake and serve cake warm with ice cream.

One 8-inch round cake.

Per serving: 1030 Calories (kcal); 36g Total Fat; (30% calories from fat); 16g Protein; 165g Carbohydrate; 93mg Cholesterol; 746mg Sodium Food Exchanges: 2 Grain(Starch); 1 1/2 Lean Meat; 0 Vegetable; 1 Fruit; 7 Fat; 7 1/2 Other Carbohydrates