Preheat oven to 350ºF. Grease & flour two 8-inch round cake pans.
Place beet chunks and buttermilk in a blender or small food processor. Blend on high until completely pureed and smooth.
Pour batter into prepared cake pans and bake for 20-22 minutes or until a toothpick inserted in the middle comes out clean. Let cakes cool in pans on wire rack for 12-15 minutes. Turn cakes out onto rack to cool completely.