Take the radicchio apart into individual leaves and remove and discard the white parts, keeping only the purple parts of the leaves.
Melt the butter in a skillet.
Saute the onion until translucent.
Add the radicchio leaves and saute until they are starting to wilt (about 2 minutes).
Add the cream and bring to a boil.
Add the chicken broth and dissolve in the cream.
Take off the heat and serve over rice.