Place unpeeled garlic cloves in a small saucepan, cover with about an inch of water, bring to a boil and then simmer 5 to 6 minutes. Remove cloves from water, peel then finely mince or press. Set aside.
In a small bowl, combine tomatoes, basil, and vinegar. Set aside.
Cook fettuccine noodles according to package directions and drain.
Melt Challenge Spreadable Butter in a large skillet over medium heat. Add onions, garlic, and chicken; sauté until lightly brown (about 5 minutes per side.)
Divide cooked pasta between individual serving plates. Arrange chicken slices on pasta, and then pour seasoned butter remaining in the cooking pan over the chicken slices. Top with tomato-basil mixture. Serve.