Preheat oven to 350 °F.
Mix ½ c brown sugar, 15 oz can pumpkin puree, mash in 4 ripe bananas. Add 2 large eggs, 1 tsp vanilla extract, and then fold in ½ c walnuts.
Whisk 2½ c ap flour, 1 tsp baking powder, 1 tsp cinnamon, ½ tsp baking soda, ½ tsp salt, ½ tsp ground nutmeg, ½ tsp ground ginger. Add to wet ingredients and mix
Prepare muffin tins with muffin cups or oil. Spoon batter into cups until mostly full. The dough won't rise much while baking so it's fine if you fill them all the way.
Bake muffins for 25 minutes, or until toothpick comes out clean.