Mix the milk, butter, egg, and sour cream until smooth in a large bowl.
Sift flour, baking powder, sugar, and salt together in a smaller bowl.
Add the dry mixture to wet mixture while stirring continuously. The batter may be lumpy.
Add the vanilla and fold in the mashed bananas.
Spray griddle with nonstick spray. Turn heat to medium; heat until grill is hot. Pour circles of batter onto the grill, cooking until bubbles rise in the center. Flip pancakes and cook remaining side until the pancakes are golden brown.
Serve topped with syrup, additional sliced bananas and chopped pecans.
Alternatively, serve topped with powdered sugar and whipped cream.