1⁄2 cup unsalted butter, room temperature, additional for pan
3⁄4 cup firmly packed brown sugar
1⁄3 cup sour cream
11⁄2 cups all-purpose flour
2 teaspoons baking powder
1⁄2 teaspoon baking soda
1⁄8 teaspoon salt
1 cup mashed bananas (2 large)
½ cup chopped walnuts, plus more for garnish
Preheat oven to 350°F. Grease 9-x-5-inch loaf pan.. Line bottoms with parchment paper.In bowl of electric mixer, beat butter and sugar until light and fluffy. Add eggs one at a time, beating well after each addition. Mix in sour cream. In separate bowl, whisk together flour, baking powder, baking soda, and salt. Add to butter mixture and beat on low speed for 1 minute. Stir in bananas and walnuts until combined. Spread batter evenly into prepared pans. Bake for 50 to 55 minutes, or until skewer inserted in centre comes out clean. Remove from oven and let cool completely.
Frost top of loaf with maple icing. Sprinkle with additional chopped walnuts if desired.
Maple cream-cheese icing
6-ounces cream cheese, softened
1/3 cup unsalted butter, softened
1/4 cup pure maple syrup
1 teaspoon pure vanilla extract
Beat together cream cheese, butter, and vanilla, scraping down sides of bowl. Add maple syrup and beat until smooth. Cover and chill until ready to use.