Adjust rack to top position and preheat oven to 450 degrees. Wash and dry all produce. Trim and thinly slice scallion, separating whites from greens. Trim and halve zucchini lengthwise; cut crosswise into 1/2-inch-thick half-moons.

Heat a drizzle of oil in a small pot over medium-high heat. Add scallion whites and cook until softened, 1 minute. Add couscous and a pinch of salt and pepper. Cook, stirring, until toasted, 2-3 minutes. Add 3/4 cup water (11/2 cups for 4 servings) and bring to a boil. Once boiling, cover and reduce heat to low. Cook until tender, 6-8 minutes. Keep covered off heat until ready to serve.

Toss zucchini on a baking sheet with a drizzle of oil and a pinch of salt and pepper. Roast, tossing halfway through, until browned and tender, 14- 16 minutes. Remove from oven; cover until ready to serve.

Pat chicken dry with paper towels; season all over with salt and pepper. Heat a drizzle of oil in a large pan over medium-high heat. Add chicken and cook until browned and cooked through, 5-7 minutes per side. (TIP: If chicken begins to brown too quickly, reduce heat to medium.) Turn off heat; transfer to a plate. Wipe out pan.

In a small bowl, combine stock concentrate, jam, and 2 TBSP water (3 TBSP for 4 servings). Heat a drizzle of oil in same pan over medium heat. Add cranberries and cook, stirring, until slightly softened, 1-2 minutes. Pour in stock mixture. Bring to a simmer and cook until thickened, 1-2 minutes. Turn off heat; stir in 1 TBSP butter until melted. Add chicken and turn to coat in sauce.

Fluff couscous with a fork; stir in 1 TBSP butter (2 TBSP for 4 servings) and half the scallion greens. Season with salt and pepper. Divide couscous, zucchini, and chicken between plates. Top chicken with any remaining sauce. Garnish with remaining scallion greens and serve.