Preheat oven to 350 degrees Fahrenheit. Line an 8- or 9-inch round cake tin with a circle of parchment paper on the bottom for easy removal. Grease the parchment and sides of the pan with a little coconut oil. Set aside.
In a large bowl, mix together the buckwheat flour, almond flour, coconut sugar, baking soda, ginger, and salt. Add in the remaining ingredients; stir to combine fully.
Pour into prepared cake pan and bake for 30 minutes, until a toothpick inserted in the center comes out clean. Let cool in the pan for 10 minutes before transferring to a cooling wrack. Once cool, store covered in the refrigerator for up to 5 days or freeze for up to 2 months.
This recipe can also be made into muffins: Divide mixture evenly between 8 muffin papers set in a muffin tin. Bake for 15 minutes and check for doneness; cook for additional time until baked through, checking often to avoid over-baking.
Cool and store covered in the refrigerator or freezer as per the cake instructions.