Just pour each colored batter into the center (slowly!) on top of each other. The layers should keep getting pushed back to form the rings. May try this with varieties of chocolate, first.
The Making of a Heisenberg (once again) by Tom Trager. Seriously, I love everything by Tom Trager. They're all great, so I'd be happy with anything he does.
Sixteen Candles Menu, Ladies 2XL