Spray cooking spray or grease and flour 4 mini loaf pans (5.91 in. L by 3.15 in W by 1.65 in. H). Set aside.
In a medium bowl, mash the bananas, leaving them a bit chunky. Set aside.
In a stand mixer fitted with the paddle attachment, or in a large bowl with a handheld electric mixer, beat together the butter, brown sugar, eggs, and vanilla extract until well blended.
½ cup unsalted butter, 1 cup light brown sugar, 2 large eggs, 1½ teaspoon vanilla extract
Add in the mashed bananas and mix until combined.
5 medium bananas
Add the flour and beat until just combined.
1¾ cups self-rising flour
Pour the batter into the prepared pans, dividing evenly.
Place pans into air fryer basket. One basket usually holds two pans. Bake in two batches if you have a single basket air fryer.
Return basket(s) to air fryer, set temperature to 325 F (163 C), and air fry for 15 minutes. Drop temperature to 300 F (149 C) and continue air frying for another 8-10 minutes, or until a skewer inserted into the center of the bread comes out clean. Remove basket(s) and allow to cool.