Start by preheating your oven to 375°F so it's fully hot by the time your batter is ready. Lightly coat an 8-inch square baking dish with cooking spray or a thin layer of coconut oil. Having this step done early keeps the whole process moving smoothly.
In a large bowl, combine the oats, baking powder, cinnamon, cloves, ginger, and salt. Stir everything together well so the spices are evenly distributed throughout the oats. This step only takes about a minute but makes a real difference in the final flavor.
Pour in the almond milk, sliced bananas, maple syrup, molasses, melted coconut oil, flaxseed, and vanilla extract. Stir the mixture thoroughly until everything is fully combined and no dry oats remain at the bottom of the bowl.
Gently fold in a quarter cup of walnuts, being careful not to overmix the batter at this point. This keeps a little texture and crunch scattered throughout instead of everything turning uniformly soft.
Pour the mixture into your prepared baking dish and scatter a few extra walnuts across the top. Bake for 30 to 35 minutes, until the top turns golden brown and the center feels set rather than jiggly.
While the oatmeal bakes, warm the coconut butter, maple syrup, and almond milk together in a small saucepan until smooth and pourable. Once your oatmeal is done, let it cool for a few minutes, then drizzle the icing generously over the top before serving.