Recipe(tried): Viennese Bonbon Ribbons - found the recipe!

I'm very happy to report that I found my mother's recipe box at my Dad's house, and it had the recipe in it... it was indeed clipped from a magazine - tho' I don't know which one. The recipe follows:

VIENNESE BONBON RIBBONS
Makes 48 small bars

1 cup (2 sticks) butter or margarine, softened
1 cup sugar
4 eggs, separated
2 cups sifted flour
FOR FILLING:
1 cup dairy sour cream
1/2 cup finely chopped walnuts
6 tbsp red currant jelly
4 tbsp apricot jam
FOR TOPPING:
Vanilla Cream Frosting (recipe follows)
tinted sugars

Cream butter or margarine until light in large bowl; gradually add sugar, creaming well after each addition; add egg yolks all at once and beat well; stir in flour until it disappears completely; set aside.

Beat egg whites until stiff enough to form soft peaks in medium-size bowl; fold into batter.

Invert a jelly-roll pan (15x10x1); butter and flour underside lightly; measure 1/3 the batter into center of pan; spread thinly almost to edges.

Bake in moderate oven (350 degrees F) 10 minutes, or until golden-brown around edges. Carefully cut in half crosswise; remove to wire rack to cool.

Repeat spreading and baking remaining batter 2 times more to make 6 very thin cake layers. Be sure to wash, butter and flour underside of pan before each baking.

TO FILL THE LAYERS:
Combine sour cream and walnuts; set aside.

Place 1 cake layer, top side up, on a cutting board; spread thinly with 2 tablespoons red currant jelly, then with a generous 2 tablespoons sour-cream mixture. Add a second layer and spread with 2 tablespoons apricot jam and 2 tablespoons sour-cream mixture; repeat with last 4 layers, alternating jelly-cream and jam-cream, leaving top plain.

Top with a second cutting board to weigh down layers; chill overnight.

THE NEXT DAY:
Trim off crust edges; spread Vanilla Cream Frosting thinly on top; sprinkle lightly with tinted sugars. Cut crosswise into 12 strips, each about 3/4 inch wide; cut each strip into 4 lengths to make 48 ribbon cakes.

VANILLA CREAM FROSTING
Makes about 3/4 cup

3 tbsp butter or margarine
1 1/2 cups 10X (confectioners' powdered) sugar, divided use (as needed)
1 tbsp cream
a dash of salt
1 tsp vanilla

Cream butter or margarine until soft in bowl; stir in 3/4 cup of the powdered sugar, then the cream, salt, and vanilla. Gradually add more powdered sugar (about 3/4 cup) until mixture spreads easily.