Eating in class usually meant spending time in detention. But for the students in Marci Arthur's classroom, it's part of the lesson plan. Arthur has been leading cooking classes at Truffles & Trifles Gourmet Kitchen Shop for 30 years. The 6,000-square-foot location in College Park is a chef's dream come true, with Arthur and her staff teaching in a fully stocked kitchen adjoining the shop. Everyone from weekend gourmets looking to add a new recipe to their repertoire to CEOs on a team-building…