Before starting, preheat the oven to 425°F. Wash and dry all produce. Add 10 cups water and 2 tsp salt to a large pot (use same for 4 ppl). Cover and bring to a boil over high heat. Meanwhile, peel, then cut onion into 1/4-inch pieces. Pat chicken dry with paper towels. Season all over with Italian Seasoning, salt and pepper.

Heat a large non-stick pan over medium heat. When hot, add 1 tbsp oil (dbl for 4 ppl), then chicken. Sear until chicken is golden-brown, 2-3 min per side. Transfer chicken to a parchment-lined baking sheet. Sprinkle with half the Parmesan. Bake in the middle of the oven until chicken is cooked through, 10-12 min.**

Meanwhile, add penne to the boiling water. Cook uncovered, stirring occasionally, until tender, 10-12 min. Reserve 1/4 cup pasta water (dbl for 4 ppl), then drain.

Meanwhile, heat the same pan (from step 2) over medium. When hot, add 2 tbsp butter (dbl for 4 ppl), then green peas and onions. Cook, stirring occasionally, until tender-crisp, 5-6 min. Season with salt and pepper.

Add pesto, penne and reserved pasta water to the pan with green peas. Cook, stirring often, until penne is coated, 1-2 min. Season with salt and pepper. Remove the pan from the heat. Add 1 tbsp butter (dbl for 4 ppl, then toss until penne is coated, 1 min.

Slice chicken. Divide chicken and penne between plates. Sprinkle remaining Parmesan over top.