Preheat oven to 170° C or 350° F. In a bowl, stir the buckwheat groats together with seeds, nuts, coconut, and spices. In a separate small bowl, smash the banana with a fork and add to the groats mixture, along with olive oil and maple syrup. Stir until everything is nicely coated. Spread across a baking sheet (lining it makes for easier clean-up) and bake for 20 to 30 minutes, stirring once halfway through, until fragrant and golden. Let cool before storing in a glass container.