Preheat oven to 350 with rack in the middle. Grease a loaf pan with coconut oil and dust with buckwheat flour.
Mash your bananas with a fork in a large bowl. When there aren’t any lumps left, mix in buckwheat flour, cinnamon, cardamom, and salt.
In a mix master (or large bowl with a hand mixer), add MCT oil, honey, baking soda and apple cider vinegar. Mix to combine. Add flour mixture to the liquid mixture and mix to combine.
Pour the batter into the loaf pan. Once full, bang the bottom of the pan onto a hard surface to replace any air bubbles. Bake in the oven for 45 minutes or until the sides have browned. Run a butter knife along the inside edges.
Let the loaf pan cool before taking it out. To remove, hold a cooling rack to the top of the pan and quickly flip. You may have to wiggle or hit the bottom of the loaf pan for the bread to come out. With the banana bread upside down on the cooling rack, place a plate on the bottom side of the bread. Holding the plate and the cooling rack, flip again so that the banana bread is right side up on the plate.