Wash and dry all produce. Adjust rack to middle position and preheat oven to 425 degrees. Bring a large pot of salted water to a boil. Zest lemon until you have 1 tsp zest, then cut into quarters. Place sour cream in a shallow dish. In another shallow dish, mix panko, Italian seasoning, lemon zest, paprika, and half the Parmesan. Season with plenty of salt and pepper.

Line a baking sheet with aluminum foil and sprinkle with a drizzle of olive oil. Pat chicken dry with a paper towel. Season with plenty of salt and pepper. Coat chicken all over with sour cream, then dip into panko mixture, coating all over and pressing to adhere. Transfer to foil-lined sheet.

Bake chicken on middle rack until cooked through, 35-40 minutes. (TIP: Chicken is done when thickest part of thigh reads 165 degrees on a thermometer.) Meanwhile, trim, then thinly slice scallions, separating greens and whites. Once water boils, add macaroni to pot. Cook, stirring occasionally, until a bit shy of al dente, 7-9 minutes.

After 7-9 minutes, add peas to pot with macaroni. Cook until peas are tender and macaroni is al dente, about 2 minutes. Reserve 1/2 cup cooking water, then drain. Return empty pot to stove, add garlic herb butter, and melt over medium heat. Add scallion whites and cook, stirring occasionally, until slightly softened, about 1 minute.

To pot with scallion whites, add 1/4 cup cooking water, remaining Parmesan, and Italian, Monterey Jack, and cream cheeses. Whisk until smooth and creamy. Gently stir macaroni and peas into pot. (TIP: Everything should be coated in a loose sauce. If thick, add more cooking water 1 TBSP at a time until creamy.) Season with salt and pepper.

Divide pasta and chicken between plates. Sprinkle with scallion greens and serve with lemon quarters on the side for squeezing over.