In a large bowl, whisk together flours, sugar, baking powder, baking soda, and salt.

In a separate bowl or large measuring cup, whisk together buttermilk, eggs, butter, and vanilla. Pour wet ingredients into dry ingredients; mix until just combined.

Heat a griddle over medium-high heat. Brush heated griddle with butter, then wipe excess butter off with a paper towel. Pour batter onto griddle; top with slices of banana and crumbled bacon. Cook until bubbles form and burst on top of pancakes, about 3 minutes, then flip and cook until golden on the underside, another 1-2 minutes. Serve pancakes warm with butter and maple syrup and additional banana slices and bacon if desired.