GRILL DIRECTIONS: Prepare grill for cooking with indirect heat. Heat grill to medium heat. In small skillet, heat oil over medium heat until hot. Add onion and garlic; cook 3 to 4 minutes or until lightly browned. Remove skillet from heat. With slotted spoon, remove onion and garlic; place in medium bowl. Add spinach and cheese to onion mixture; mix well.
Lift skin from thin side of turkey breast; carefully tuck spinach mixture into cavity under skin. Secure with toothpicks. Add marmalade to remaining oil in skillet; mix well.
When ready to grill, place drip pan in center of grill with gas heat or charcoal at edges. Place turkey breast, skin side up, on grill rack directly over drip pan; cover grill. Cook 1 to 1 1/2 hours or until turkey is fork-tender and juices run clear, brushing occasionally with marmalade mixture during last half of cooking time.
Remove turkey from grill; cover with foil. Let stand 10 minutes before carving.