Rhubarb Dessert Soup

Rhubarb is a terribly underutilized vegetable: the few who knows of its existence cannot see past the pie or, in the US, past the strawberry rhubarb pie. By the way, I never quite understood why one would hide the delicious tang or tartness of the rhubarb with sweet strawberry: the tang is the best part! And when rhubarb gets elevated by cinnamon and vanilla, and perhaps a hint of nutmeg, it transcends to the divine.