Cream the butter and sugar together until fluffy. Beat in the sour cream and the egg.
Mash the bananas with the back of a fork. Make sure to get the little lumps out. Add the bananas and the vanilla to the butter and sugar and blend well.
Sift the flour, salt and baking soda and add to the batter. Stir just until combined. Fold in the nuts.
Spread the batter into an 8x8 or 9x9 square baking pan that's been sprayed with oil or lined with parchment paper with overlapping ends. The paper will help you remove the cake from the pan for neater cutting.
Bake for about 25 to 30 minutes until a toothpick comes out without wet batter clinging to it. (It will still be moist)
Let cool before frosting.
To make the frosting, heat the butter and sugar in a small saucepan until it comes to a boil, stirring to dissolve the sugar. Cook for 2 minutes.
Take off the heat and add the heavy cream, vanilla and salt.
Beat in the powdered sugar, and continue beating on high until the frosting is thick and glossy. Add a little more cream if it seems too thick, and a little more sugar if it seems too thin.
Nutritional information is provided as a courtesy and is an estimate only. This information comes from online calculators. Although The View from Great Island attempts to provide accurate nutritional information, these figures are only estimates.
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