In the past, I have made buckwheat crepes and bread. Up till now, I have never made a cake with it. Then I found one from a French blog, and although I tried it, it came into some difficulties and choices. For fat, I used olive oil instead of butter. And though the recipe called for store-bought cassis, I made some cranberry jam as a substitution.
This cake has a wonderful sponge texture, moist, grassy and not sweet. I think the method of incorporating oil could be different to; maybe whipping the yolks while slowly incorporating the oil to emulsify, then adding in the sugar. Why? Because the oil sort of drowned out the sugar when I tried to thicken it. Though with butter, which is solid, it would make a huge difference! Still I think it was just perfect and rustic.