Preheat your oven to 175 degrees Celcius / 350 Fahrenheit. Line an 8 inches square baking pan with parchment paper.
In a big bowl, mash the bananas. Add peanut butter, plant milk, vanilla extract and coconut blossom sugar and mix very well.
In a seperate bowl, combine oat flour, baing powder and baking soda. Then add the dry ingredients to the wet ones.
Combine until you have a smooth and thick batter. Fold in chopped walnuts and 3/4 of the chopped dark chocolate.
Pour the batter into the prepared pan. Slice up a banana lengthways and place it on top of the batter, then add the rest of the chopped dark chocolate.
Bake for 30 to 35 minutes until golden brown on top and a toothpick inserted in the center of the blondies comes out clean. Let them cool down in the pan completely before cutting them into squares.