Adjust rack to top position and preheat oven to 450 degrees. Wash and dry all produce. Trim and slice zucchini into ⅓-inch-thick rounds. Trim and thinly slice scallions, separating whites from greens. Zest and halve lemon (for 4 servings, zest 1 lemon and halve both).

Toss zucchini on a baking sheet with a large drizzle of olive oil, half the Tuscan Heat Spice (you’ll use the rest in the next step), salt, and pepper. Roast on top rack until golden brown and tender, 14-16 minutes.

Meanwhile, pat chicken dry with paper towels; season with salt, pepper, and remaining Tuscan Heat Spice. Heat a large drizzle of oil in a large pan over medium-high heat. Add chicken and cook until browned and cooked through, 3-5 minutes per side. Turn off heat; transfer chicken to a plate. Wipe out pan.

While chicken cooks, heat a drizzle of oil in a small pot over medium-high heat. Add scallion whites; cook until softened, 1 minute. Add couscous; stir until toasted, 30 seconds. Add ¾ cup water (1½ cups for 4 servings), half the stock concentrates (you’ll use the rest in the next step), and a pinch of salt. Cover and bring to a boil. Once boiling, reduce heat to low. Cook until couscous is tender, 6-8 minutes. Keep covered off heat until ready to serve.

Once zucchini is tender, remove sheet from oven. Heat broiler to high. Sprinkle zucchini with panko and mozzarella. Broil until browned and crispy, 2-5 minutes. (TIP: Watch carefully to avoid burning.) Heat pan used for chicken over medium-high heat. Add remaining stock concentrates, ¼ cup water (⅓ cup for 4 servings), and a squeeze of lemon juice to taste. Simmer until slightly reduced, 2-3 minutes. Stir in sour cream and 1 TBSP butter (2 TBSP for 4). Season with salt and pepper. Turn off heat.

Add 1 TBSP butter (2 TBSP for 4 servings), half the lemon zest, juice from half the lemon (whole lemon for 4), half the scallion greens, salt, and pepper to pot with couscous; stir to combine. (TIP: If couscous seems dry, add a splash of water.) Divide couscous, chicken, and zucchini between plates. Spoon sauce over chicken. Top with remaining scallion greens and lemon zest and serve.