I love cakes that contain all sorts of flavors and textures. This Rhubarb Streusel Cake Recipe with Vanilla Cream (Rhabarbarkuchen mit Vanillecreme) does just that. The base is simple, and the Vanilla Cream filling is sweet (but not too sweet) and smooth. Over a pound and a half of tart rhubarb, topped by sweet, crunchy streusel, completes the picture. Altogether,…