The thief cannot be Franque or Elvira, as neither of those play EQ (EQ Is relevant, as it is the game that has a level 82 Cleric..)
Jackie and Vladimer are both also out of the running for thief, as it seems highly unlikely that they would talk about their Pumpkin Pie recipes, when neither likes pumpkin pie.
This leaves Mumsie and Moldie.
It cannot be Mumsie, as the main food listed that has sprinkles is Cupcakes, which she does not like. Leaving the most logical thief to be Moldie.