Preheat the oven to 350F. Using an electric mixer on medium-high, beat the butter and sugars in a large bowl until smooth and creamy. Beat in the eggs, one at a time, then beat in the bananas and vanilla. In a separate bowl, mix together the flour, baking soda, salt, cinnamon, cardamom, and allspice. Add the flour mixture to the banana mixture and fold in with a spatula until well blended. Gently fold the nuts and sour cream into the batter until just blended, being careful not overmix.