Loaded Banana Bread

2 cups all-purpose flour
2 teaspoons baking powder
1/2 teaspoon baking soda
1 teaspoon table salt
1/2 cup butter, room temperature
1 cup granulated sugar
2 eggs
4 ripe, nasty looking bananas, smooshed up real good
1/3 cup buttermilk
1 cup walnuts, coarsely chopped and toasted
1 cup shredded, sweetened coconut
1 cup blueberries, fresh or frozen (thawed), plus a handful for sprinkling on top
1 Tablespoon pure vanilla extract