In a small bowl, mix the first 9 ingredients., Slice zucchini lengthwise into twenty-four 1/8-in.-thick slices. On a greased grill rack, cook zucchini in batches, covered, over medium heat. Grill until tender, 2-3 minutes on each side., Place 1 tablespoon ricotta mixture on the end of each zucchini slice. Roll up and secure each with a toothpick.