Hi Marianne :-) Here are two recipes that I found on the internet. I have not tried them. I hope one is close to what you are looking for.

Banana Sour Cream Torte

1/2 cup butter
1 1/2 cups sugar
2 eggs, beaten
1cup mashed bananas
1cup sour cream
1 tsp baking soda
2 cups cake flour (I use reg. and sift a lot)

Grease & line 2 layer pans with wax paper. Mix & bake 350-370 F 20-25 min.

FILLING
1cup sour cream
1 egg yolk
1/2 cup sugar
2 Tbsp cornstarch

Cook in double boiler until thick. Add the egg yolk after you remove the filling from the burner. Spread filling on both layers and on sides. Sprinkle chopped walnuts on top and sides. (I never did figure out how my mom sprinkled them on the sides!). Refrigerate.

NOTES: You could probably lower the fat in this by substituting no-fat sour cream. I would recommend going 50/50 real sour cream and no fat sour cream for the filling. The egg yolk could be replaced by extra corn starch and a drop of yellow food coloring. I experimented with the 50/50 option and the filling loses its translucent quality but the consistency and flavor remain.

I usually make 1 1/2 batches of filling because I think it is skimpy on the filling otherwise.

Banana Nut Torte
Moist banana nut cake, rich cream filling topped with whipped cream!
Yield: 9 servings

Cake:
1 cup sugar
1/2 cup butter or margarine, softened
3/4 cup mashed ripe bananas
1 teaspoon vanilla
2 eggs
2 cups all-purpose flour
1 teaspoon baking soda
1 teaspoon baking powder
1/2 teaspoon salt
1/2 cup dairy sour cream
1/2 cup chopped pecans

Filling:
1 cup milk
1/2 cup sugar
3 tablespoons all-purpose flour
1/4 teaspoon salt
2 egg yolks
1 teaspoon vanilla

Topping:
Powdered sugar
Sweetened whipped cream or frozen whipped topping, thawed

Preheat oven to 350 degrees F. Grease and flour a 9 inch square cake pan.

In a large mixing bowl, beat 1 cup sugar and margarine or butter until light and fluffy. Add bananas, 1 teaspoon vanilla and 2 eggs. Mix well. Gradually add 2 cups flour, baking soda, baking powder and 1/2 teaspoon salt. Mix well. Blend in sour cream; stir in nuts. Pour batter into the prepared pan.

Bake at 350 degrees F. for 40 to 45 minutes or until toothpick inserted in center comes out clean. Cool 5 minutes; remove form pan. Cool completely.

In a medium saucepan heat milk until very hot, but do not boil. In medium bow, combine 1/2 cup sugar, 3 tablespoons flour and 1/4 teaspoon salt. Stir in hot milk; mix well. Return mixture to saucepan and cook oven medium heat until the mixture boils an thickens (about 4 to 5 minutes) stirring constantly. In small bow, beat 2 egg yolks; gradually blend 1/4 of the hot milk mixture into the yolks. Add egg yolk mixture to saucepan and cook for another 2 to 3 minutes, stirring constantly. Remove from heat and stir in 1 teaspoon vanilla. Cool.

To assemble the torte, slice cooled cake horizontally forming 2 layers. Spread filling between layers. Sprinkle powdered sugar over the top layer. Serve with sweetened whipped cream or whipped topping.