Melt the butter in a pan over medium heat. Add the brown sugar and stir to combine. Add the bananas and stir to coat, cooking until browned on each side and the brown sugar has clumped (about 5 minutes total).
MAKE THE PANCAKES:
Preheat a skillet or griddle to medium-heat.
In a medium-bowl, whisk together the flour, sugar, brown sugar, baking powder and salt.
In another bowl, mix together the milk, egg, butter, vanilla and mashed bananas. Add the dry ingredients to the wet ingredients and mix until just combined (don’t over-mix). Gently stir in the nuts.
Lightly grease the preheated skillet or griddle. Scoop ¼ cup of batter onto the skillet. Cook for 1 to 2 minutes, until the edges begin to look “dry.” Flip with a spatula, cook another 2 minutes. Repeat with the remaining batter. Serve topped with the caramelized bananas. Maybe add a little maple syrup and a few more walnuts too.