Preheat the oven to 350° F.
Spray, or grease, and flour a loaf pan.
To avoid a so-called “wet log” (a moist and uncooked block forming in the bottom of the loaf due to high-moisture bananas), mix the mashed bananas and sugar thoroughly for 5-7 minutes, and cook them in a pan.
Simmer them on medium heat for 10 minutes to reduce moisture and caramelize the bananas, and get a much bolder banana flavor in your loaf. Let it cool down to room temperature before proceeding.
Bring eggs, melted butter, and the banana-sugar mash to room temperature.
To avoid a mushy or undercooked texture, we have to mix the wet and dry ingredients separately, avoiding overmixing the batter.
Beat the eggs, and gradually add the butter, sugar-banana mix, vanilla extract, maple syrup, sour cream, and lemon zest.
Add each ingredient, one-by-one, whisking for a few seconds after each.
Alternatively, you can whisk the wet ingredients in a mixer.
In a separate bowl, combine all the dry ingredients well, sifting the flour.
Gently fold the wet ingredients into the dry mixture with a spatula. Stop the gentle mixing as soon as it is evenly distributed, to avoid overmixing.
Immediately pour the batter into the greased, floured pan. Don’t shake or bang the pan, as it releases the air from the batter, and you might get a flat, gummy-textured loaf.
Bake the banana bread in the preheated oven for 55-70 minutes.
After 50 minutes, start checking the loaf by inserting a toothpick in the middle, and see if it comes out clean. Repeat every 10 minutes, after the 50-minute benchmark, until the banana bread is ready.
After the bread is ready and cooked just well, let it sit and cool for 15-20 minutes before cutting.
It has to solidify some more. By cutting it oven-warm, you risk getting crumbly and dry banana bread.