Preparation Blend 1 cup yogurt and next 10 ingredients in processor until smooth. Transfer to large bowl. Mix in remaining 1 cup yogurt. Add chicken and turn to coat. Cover and refrigerate overnight. Prepare barbecue (medium-high heat). Place marinade-coated chicken on barbecue. Grill chicken until just cooked through, occasionally basting with butter last 2 minutes, about 12 minutes per side. Transfer chicken to platter. Top with onion and cilantro and serve.
Preparation Blend 1 cup yogurt and next 10 ingredients in processor until smooth. Transfer to large bowl. Mix in remaining 1 cup yogurt. Add chicken and turn to coat. Cover and refrigerate overnight. Prepare barbecue (medium-high heat). Place marinade-coated chicken on barbecue. Grill chicken until just cooked through, occasionally basting with butter last 2 minutes, about 12 minutes per side. Transfer chicken to platter. Top with onion and cilantro and serve.