In a small saucepan, bring the chicken stock to a boil and reduce until it is syrupy about 1 or 2 Tbsp Sauté the shallots in the butter and add both the stock syrup and the shallots to the MASA mixture. Spread 2 heaping Tbsp of the MASA on a large piece of corn husk - you may have to layer two overlapping then put a long thin piece of Rillettes in the center.
Cover with more MASA if necessary to surround it when rolled. Roll up and tie the ends with a thin piece of corn husk or string. Steam in a bamboo or vegetable steamer for about 30 minutes.
Servings: 6