When Heatherlee Muehlius' new food truck hit the streets a month ago, she most likely became the best educated restaurateur on wheels in Milwaukee. Known as Hattie, Muehlius has a culinary degree from Moraine Park Technical College in Fond du Lac, and bachelor and master's degrees in education. For most of the year she is an English as a second language specialist in the Milwaukee Public Schools, but this summer she has become the owner and operator of Hattie's Truck.