Preheat oven to 350 degrees. Spray a loaf pan with cooking spray and set aside.
In a large bowl, cream together the mashed bananas, yogurt, butter, eggs, and sugars until well combined. In the same bowl, beat in the flour, flaxseed, cinnamon, baking soda, and salt. Fold in the dried cranberries and walnuts.
Pour battter into prepared loaf pan. Bake for 55 to 60 minutes, or until a toothpick inserted in the center comes out clean. Remove from oven and let cool in pan for 10 minutes before removing from pan and letting cool completely on a wire rack.
To make the glaze, whisk together the powdered sugar, milk, and vanilla. Pour glaze over cooled loaf.
Notes
This Cranberry Walnut Banana Bread can be made ahead and stored in the refrigerator in an airtight container for up to a week. Alternatively, you can freeze in an airtight container for up to two months.