Preheat oven to 200°.
In a large mixing bowl whisk the buttermilk, eggs, and vanilla together until well combined. In a separate bowl mix the flour, baking powder, baking soda, salt, and sugar. Combine the wet ingredients with the dry and stir until lumps are gone. Fold in the pecans, most of the melted butter, and whisk until batter is smooth. Heat skillet over medium low heat and swirl a little butter.
Cook the pancakes on 1 side until they are set and then lightly press the bananas into the batter. When small bubbles appear on the uncooked surface, flip the pancakes and cook until golden on both sides, about 8 minutes. Transfer pancakes to a warming plate in the oven.
For the maple butter, combine ingredients in a mixing bowl. Roll it up with greaseproof paper, twist edges, and chill in refrigerator for about 30 minutes.