Particles or Fluid will save your backside. A particle system of blobby particles/metaballs (your chocolate) and and a rigid body (your ice cream) miiiiiiight just work. I suggest you buy the Learning Maya 7 Special Effects Handbook, there are some pretty detailed articles about the principles of blobby surfaces. Searching the dynamics forum for these keywords may be helpful. The manual also has the basic principles of particles, rigid bodys and metaballs in it.
Now, go go go, get out there and do your job, oh and remember, no sleep till deadline! 