Mandarin Orange Sour Cream Cake

I loved spending summer afternoons at my aunt Heidrun’s house for two main reasons: sunbathing with my cousin Anna by their private pool (a rare luxury in Germany) and eating a few slices of this mandarin orange sour cream cake; it always lit me up when my aunt made it. Years later, these are still two of my favorite things to do—only now, my cousin and I have our own kids splashing in the pool and we have to share this cake with them. The cake has a soft, moist base, a bri