The executive chef at Painted Burro and Posto, Joe Cassinelli, and Rosebud American Kitchen & Bar chef John Delpha (pictured) are offering monthly cooking classes on Saturdays at their sibling restaurants that includes. — including Posto. Classes will rotate among the three Davis Square locations. On May 16 the subject is festive summer dishes, June 20 is summer entertaining, July 18 is BBQ 101, and Aug. 22 will explore the flavors of summer. Tickets ($55) are slightly discounted if you buy more than one place at a class. Each is two hours with 10 students only. The chefs will pair drinks and dishes and students will participate in the preparation and get to eat what they make. Cooking class tickets at www.eventbrite.com. Posto, 187 Elm St., Davis Square, Somerville, 617-625-0600; The Painted Burro, 219 Elm St., Davis Square, Somerville, 617-776-0005;Rosebud American Kitchen & Bar,381 Summer St.,Davis Square,Somerville,617-629-9500.