Bring a large pot of salted water to a boil.

Meanwhile, wash and dry produce. Trim and thinly slice scallions, separating whites from greens. Zest and quarter lemon.

Once water is boiling, add spaghetti to pot. Cook, stirring occasionally, until al dente, 9-11 minutes.

Reserve ½ cup pasta cooking water, then drain.

While spaghetti cooks, pat chicken* dry with paper towels and season all over with half the garlic powder (you’ll use the rest later), salt, and pepper.

Heat a drizzle of oil in a large pan over medium-high heat. Add chicken; cook until browned and cooked through, 5-7 minutes per side.

Turn off heat; transfer to a cutting board and tent with foil to keep warm. Wipe out pan.

Once spaghetti is drained, heat a drizzle of oil in pan used for chicken over medium-high heat. Add scallion whites and cook, stirring, until softened, 30-60 seconds.

Stir in drained spaghetti, peas, cream sauce base, onion paste, remaining garlic powder, and a squeeze of lemon juice. Cook, tossing, until sauce has thickened and everything is evenly coated, 1-2 minutes. (If sauce seems too thick, stir in reserved pasta cooking water a splash at a time.) Taste and season with salt and pepper.

Slice chicken crosswise.

Divide pasta between plates. Top with chicken, scallion greens, a squeeze of lemon juice, and as much lemon zest as you like. Serve with any remaining lemon wedges on the side.