Martha's Banana Bread With Honey-Cinnamon Frosting

1/2 cup (1 stick butter), room temperature, plus more for baking pan
1 cup granulated sugar
2 large eggs
1 1/2 cups unbleached flour
1 teaspoon baking soda
1 teaspoon kosher salt
1 cup mashed very ripe bananas
1/2 cup sour cream
1 teaspoon vanilla extract
1/2 cup chopped walnuts or pecans

Preheat oven to 350 degrees F. Butter 9-inch by 5-inch loaf pan.

With an electric mixer, cream the butter and sugar until light and fluffy. Add the eggs, beating well. Sift the dry ingredients together and combine with the butter mixture. Blend well. Add the bananas, sour cream, and vanilla. Stir well. Stir in the nuts and pour into the pan. Bake 1 hour until a cake tester comes out clean. Turn out onto a rack to cool.

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Honey-Cinnamon Frosting:
1 1/4 cup confectioners' sugar
1/2 cup (1 stick) unsalted butter, room temperature
1 T honey
1/8 teaspoon ground cinnamon

In a medium bowl, using an electric mixer, beat confectioners' sugar, unsalted butter, honey, and ground cinnamon until smooth, 4 to 5 minutes