Preheat oven to 350° F. Line a baking sheet with parchment and set aside. In a bowl, stir the buckwheat groats together with the pepitas, pecans, coconut flakes, cinnamon, cardamom and coconut sugar, if using.
In a separate small bowl, mash the banana with a fork and stir in the coconut oil and maple syrup. Combine with the groat mixture and stir until evenly coated. Spread only baking sheet and bake for 20 to 30 minutes, stirring once halfway through, until fragrant and golden. Let cool before tossing with cacao nibs and storing in a glass container.