Start by peeling the bananas and breaking them into pieces. Place them in a mixing bowl. Add the eggs and blend the mixture using an immersion blender until smooth.
Melt the coconut oil in the microwave for about 1 minute. Pour the melted oil into the bowl with the bananas and eggs. Add the topinambour syrup (or your preferred sweetener), salt, baking powder, and baking soda, and stir until well combined.
Gradually add the almond flour in batches. The dough should have a thick but not too dense consistency—thicker than pancake batter but not as thick as cookie dough.
Preheat your oven to 392°F (200°C). Grease a rectangular baking mold with coconut oil. Pour the dough into the mold, spread it evenly, and sprinkle with almond petals.
Bake for 30-40 minutes. Check for doneness by inserting a toothpick into the center; it should come out clean. Allow the banana bread to cool in the mold before removing it. The bread will become firmer as it cools, making it easier to slice.