Heat oil in medium saucepan over medium-high heat.

Add onion; cook, stirring frequently, for 3 to 5 minutes, or until onion is translucent.

Add garlic; cook, stirring frequently, for 1 minute.

Add mushrooms and basil; cook, stirring frequently, for 3 to 5 minutes, or until mushrooms release liquid. Set aside.

Using a vegetable peeler, cut each zucchini into lengthwise strips about ⅛ inch thick. Turn zucchini slightly after cutting each strip to work evenly around the outside, stopping when you hit the seeds at the core. Discard cores. Cut slices lengthwise into ½- inch ribbons. Set aside.

Add zucchini to onion mixture; cook over medium-high heat, stirring frequently, for 2 to 4 minutes, or until heated through.

Add pesto; mix well.

Evenly divide zucchini mixture between two serving plates; evenly top with chicken.