½cbutter(salted, 1 stick - softened at room temperature)
1teaspoon baking soda
1teaspoon ground cinnamon
2call-purpose flour(divided, reserve ¼ c flour to coat the nuts)
½ccrushed black walnuts
Preheat your oven to 375 degrees F (190 degrees C) and either coat your muffin tin(s) with non-stick cooking spray or line with cupcake papers.
In a large mixing bowl, or the bowl of your stand mixer, cream together the butter and sugar. Add the overripe bananas and mash into the creamed butter and sugar.
Add the eggs, milk and vanilla, then mix until combined (wet batter will be very lumpy from butter and bananas).
Add baking soda, baking powder, cinnamon and salt and stir into the batter. Then add the first portion of divided flour amount (1 ¾ cups) and mix just until the flour is incorporated into the lumpy batter.
In a small ziploc bag, combine the remaining flour portion (¼ cup) with the crushed black walnuts. Shake until well coated, then add to the batter and fold in gently to distribute evenly throughout the batter. *You can add mashed bananas at this step too (vs. earlier), if you like larger chunks of banana in your muffins.
Transfer batter to prepared muffin tins, and bake at 375 degrees F (190 degrees C) for 18-20 minutes, or until an inserted toothpick comes out clean from the center of the muffins.
Remove to a wire cooling rack and allow the banana nut muffins to cool in the muffin tins for a few minutes before turning the muffins out. Serve muffins warm or at room temperature.