Preheat the oven to 350 degrees Fahrenheit and line an 8-inch square baking pan or a standard loaf pan with parchment paper.

Mash the ripe bananas in a large mixing bowl until mostly smooth.

Add peanut butter, honey or maple syrup, and vanilla extract to the mashed bananas and whisk until smooth.

Sprinkle oat flour, cinnamon, and salt over the wet mixture and stir gently until combined, forming a thick, slightly sticky batter.

Fold in dark chocolate chunks, distributing them evenly throughout the batter.

Transfer the batter to the prepared pan, pressing it down into an even layer.

Bake for 20 to 24 minutes, checking for golden edges and firmness in the center.

Cool in the pan for at least 15 minutes before lifting out and transferring to a wire rack.

Once completely cooled, slice into 12 even bars using a sharp knife.

Chill the bars in the refrigerator for 20 minutes before slicing for cleaner edges.