Associated Press - CHELSEA - The Michigan-based maker of Jiffy Mix baking mixes plans a $35 million expansion as part of an effort to diversify the business. Chelsea Milling Co. plans a new mixing tower that will eventually be attached to a new packaging plant and support building, the Ann Arbor News reported. The company plans to keep making boxes of mix for retail sale while boosting institutional and food-service sales. Howdy Holmes, the fourth-generation owner of Chelsea Milling, said the expansion