Place the cornstarch and five-spice seasoning in a small mixing bowl. Add 2 Tbs. chicken broth; whisk until smooth. Stir in remaining broth, soy sauce, and garlic. Whisk in peanut butter; set aside.
In a large nonstick wok or skillet over high heat, cook sesame seeds 3 to 5 minutes to toast, occasionally swirling the wok to prevent scorching. Pour the seeds onto a paper plate. Return wok to high heat; add oil and baby carrots. Cook about 2 minutes, stirring frequently. Mix in chicken. Add bok choy and baby spinach.
Using a large spoon, cook and stir 3 to 4 minutes, until spinach and bok choy start to shrivel. Add corn and peanut butter sauce. Cook and stir 1 or 2 minutes until sauce is thick and creamy. Sprinkle with sesame seeds. Bring the wok to the table and serve.