Cream butter, sugar, and eggs. Sift the dry ingredients and combine with butter mixture. Blend well. Add bananas, sour cream and vanilla; stir well.

Stir in nuts and pour into a well-buttered 9x5x3 inch loaf pan, several smaller loaf pans or muffin tins.

Bake until center is set and a toothpick inserted in center comes out clean (about 50-60 minutes for a larger loaf pan or 25 minutes for muffins).

Turn out onto a rack to cool.