Melt butter in saucepan over medium-high heat until sizzling. Add onions; cook 3 minutes or until softened. Stir in garlic sauce; cook 1 minute. Add coconut milk and chicken broth. Cover; cook until mixture just comes to a boil.

Uncover; add chicken, peas, bell pepper, fish sauce and rice noodles; cook until mixture comes to a boil. Continue cooking 4 minutes or until noodles are softened. Stir in lime juice.

Garnish individual servings with cilantro, if desired.