Slice eggs in half lengthwise. Remove yolks; place in small bowl. Mash yolks with fork or potato masher.
Stir in mayonnaise, Parmesan cheese, parsley, basil and garlic powder until smooth and creamy. Spoon or pipe yolk mixture into egg white halves.
Refrigerate 1 hour or until ready to serve. Top with diced tomatoes before serving.