Preheat oven to 350 degrees and place baking rack in the center of the oven. Grease and lightly flour muffin tin, set aside.
Sift together flour, baking powder and salt in a medium bowl.
Using an electric mixer, beat butter and sugar until fluffy, about 4-6 minutes. Begin adding eggs, one at a time, beating for 1 minute each. Stopping and scraping down the sides of the bowl. Add the mashed bananas and lemon juice. Mix until combined.
With the mixer running on low, all at once add the flour mixture. Mix until almost combined. Using a spatula, now incorporate the walnuts and chocolate chunks.
Fill the muffin tins ⅔ (or ¾ like mine for a larger muffin top) and bake for 45 minutes. Remove from the oven, let cool for 10 minutes, then remove the muffins and continue to cool on a wire rack.
Recipe by The Fruit Company® Blog at http://blog.thefruitcompany.com/red-banana-walnut-muffins/