Grease a loaf tin with melted butter and line with baking or parchment paper. Have at least half an inch of the paper above the tin on either side for easy removal. Grease the paper also to avoid that sticking to the bread.
Preheat you weber q on the high setting for indirect cooking.
Mash the bananas with a fork in a bowl
In a small saucepan on low heat, slowly melt your butter over the camp stove. Set aside to slightly cool.
In a large mixing bowl add sifted flours and cinamon.
Add the brown sugar and stir into the flour, breaking up any clumps of sugar with your spoon.
Whisk the eggs well and add to the dry ingredients, along with the bananas, butter, milk and walnuts.
Fold the mixture until well combined, then add the mixture to the loaf tin
Place in the center of the weber q, close the lid, and turn the heat down to the medium-high setting.
Let it bake for 55 minutes to 1 hour depending on weather conditions. Test the bread with a skewer, if it comes out clean it is ready.
Remove from the weber and set aside for 5 minutes before removing from the tin.