Preheat oven to 180°C or 350°F.
Grease a square baking dish of 24 x 24 cm (9 x 9 inches).
Add a little less than half of the blueberries in the baking dish.
In a bowl mix the oatmeal, cinnamon, allspice, ginger, walnuts and coconut. Set aside.
Add the rest of the blueberries, leaving a few for last.
In another bowl mix milk, mashed banana, vanilla and honey.
Wisk the mixture of oats and spices with the liquid ingredients. Mix.
Once everything is hydrated, pour over the buttered mold with blueberries on the bottom.
Distribute the mixture well and add the remaining blueberries on top and a little more dehydrated coconut (optional).
Bake in preheated oven for 30 to 35 minutes.
Remove from oven and let rest for at least 20 minutes before serving.