Prep the ingredients and preheat the oven to 425 degrees.
Cream butter and sugar. Blend in the eggs until well incorporated.
Add vanilla, banana and zucchini and mix until you see zucchini uniformly distributed.
Whisk together the dry ingredients and add to wet mixture. Blend together briefly. Stir in the chopped walnuts.
Line cupcake tins with paper liners. Fill each with about 1 1/2 large scoops of batter. This should make about 18 muffins.
Place in preheated oven and SET THE TIMER FOR 5 MINUTES
When the timer beeps, lower oven temperature to 375 degrees and continue to bake for 12-15 minutes.
Remove from oven to cooling rack for about 5 minutes. Then, remove muffins from the pan back to the cooling rack. Enjoy while they are warm, or store once cooled and briefly warm up in the microwave prior to enjoying.