Oh, and one other thing: I was impatient and used ripe, rather than over-ripe bananas. Fifteen minutes in a moderate oven had them perfectly black and squishy for mashing. I got the idea from this much more naughty banana recipe.
1 cup brown sugar
~3 bananas, mashed (aim for about 1 cup, I had a bit more)
1 teaspoon vanilla extract
2 cups wholemeal flour
1 teaspoon baking soda
1/2 teaspoon salt
1/2 cup chopped walnuts, optional
Preheat the oven to 180 degrees C and grease a small-medium loaf pan.
Cream the butter and sugar together in a large bowl. Beat in the eggs, banana and vanilla.
Sift together the flour, baking soda and salt into a separate bowl, then stir them into the butter mix. Add the walnuts, if you're using them.
Pour the batter into the loaf pan and bake for 45-60 minutes. Nicole specifies the full hour, but I found that mine took a lot less time!