Combine flour, salt, baking soda, and baking powder. Whisk the mixture until it is combined.
In a separate bowl, combine discard, whole milk, mashed bananas, vanilla extract, egg, melted butter, granulated sugar, and 1/4 cup brown sugar.
Mix the wet and dry ingredients together.
Fold in the chopped pecans
Grease a 12-well muffin tin
Evenly distribute batter in muffin wells.
Combine 1/2 cup brown sugar and the cinnamon.
Top each muffin with around 1 tsp of sugar-cinnamon mixture.
Bake at 350° F for 25-30 minutes.