Preheat the oven to 450 degrees F. Cut the hens in half with kitchen shears, cutting along one side of the breastbone. Place the hens on a rimmed baking sheet, cut-side down; season with salt and pepper. Scatter the lemon slices over and around the hens. Roast until the hens are golden, about 20 minutes.
Meanwhile, melt the butter in a medium saucepan over medium-high heat. Add the onion and a pinch of salt. Cook, stirring occasionally, until softened, 3 minutes. Add the couscous and cook, stirring occasionally, until lightly toasted, 3 minutes. Add the broth; season with salt and pepper. Bring to a simmer, then reduce the heat to low. Cover and cook until most of the liquid is absorbed, about 8 minutes. Stir in the zucchini, cover and cook until tender, about 3 more minutes; set aside.
Combine the honey, cumin, paprika and lemon juice. Brush on the hens and continue roasting until cooked through, 5 to 7 more minutes.
Stir the cilantro and lemon zest into the couscous and season with salt and pepper. Serve with the hens and drizzle with any pan juices.
Photograph by Charles Masters
Recipe courtesy of Food Network Magazine