Mixing Bowls

Ok... Mixing Bowls.
You definitely need more than 2 bowls.  Here at the kinds I have:

A set of Glass Bowls that are perfect for prep-ing and tasks like whipping cream and making mayonnaise.
Prep bowls are very under rated!!

Next a set of bowls that have rubber rings on the bottom and pouring spouts.  I use these for everything, the spouts are really helpful and the rubber keeps them from slipping around on the counter while mixing.

Find at:
Williams Sonoma - Glass Nesting Bowls
Williams Sonoma - Melamine Mixing Bowls