Adjust rack to middle position and preheat oven to 425 degrees. Wash and dry all produce. Trim, peel, and cut carrots into 1/2-inch-thick pieces on a diagonal. Trim and thinly slice scallions, separating whites from greens. Mince garlic.

Melt 1 TBSP butter in a small pot over medium-high heat. Add almonds and cook, stirring, until lightly browned, 2-3 minutes. Add garlic, couscous, and a pinch of salt; cook for 30 seconds. Stir in 3/4 cup water (11/2 cups for 4 servings), then cover and bring to a boil. Once boiling, reduce heat to low. Simmer, covered, until couscous is tender, 6-8 minutes. Keep covered off heat until ready to serve.

Meanwhile, toss carrots on a baking sheet with a large drizzle of olive oil, salt, and pepper. Roast on middle rack until browned and tender, 20-25 minutes.

While carrots roast, pat chicken dry with paper towels; season generously all over with salt and pepper. Heat a large drizzle of olive oil in a large pan over medium-high heat. Add chicken and cook until browned and cooked through, 5-7 minutes per side. Turn off heat; transfer to a cutting board to rest.

Heat a drizzle of olive oil in same pan over medium-high heat. Add scallion whites and cook 1 minute. Pour in vinegar, stock concentrate, jam, and 1/4 cup water (1/3 cup for 4 servings); whisk to combine. Bring to a simmer and cook until thickened, 1-2 minutes. Turn off heat; stir in 1 TBSP butter (2 TBSP for 4) until melted. Season with salt and pepper.

Stir 1 TBSP butter (2 TBSP for 4 servings) into pot with couscous; season with salt and pepper. Thinly slice chicken crosswise. Divide couscous, chicken, and carrots between plates. Top chicken with sauce. Garnish with scallion greens and serve.