To make the crust mixture, put the walnuts and butter in a food processor and process until the nuts are finely ground, stopping once or twice to scrape down the sides of the container. Add the breadcrumbs, chives, and pinch each of salt and pepper, and process until blended. Scrape into a small bowl, then cover and refrigerate for at least 2 hours, or overnight if you wish.
Coat a large baking pan with nonstick cooking spray. Season the salmon fillets lightly on both sides with salt and pepper and place them, skin-side-down, in the baking pan. Using your fingers, press and pat 2-3 tablespoons of the walnut crust mixture in a thin layer over each piece of salmon.
When you are ready to serve, preheat the oven to 400°F. Bake the salmon for 15 –18 minutes, until the crust has browned lightly around the edges.
To make the stewed kale and chickpeas, wash the kale leaves and drain them, then cut the leaves into strips about an inch wide. Set aside. Heat the olive oil in a large, deep pot over medium heat. Add the garlic and red pepper flakes and cook, stirring, for a minute or two, until the garlic begins to brown. Add the kale and season lightly with salt and pepper. Stir and toss to coat the kale with the oil and garlic mixture; then cook about 5 minutes, stirring often, until it begins to wilt. Add 1/2 cup of the chicken stock then cover the pan and cook over medium-high heat, stirring once or twice, for 15 minutes.
Add the chickpeas and the remaining 1/2 cup of chicken stock. Cover and continue cooking over medium heat, stirring occasionally, 15–20 minutes more, until the chickpeas and kale are very tender. If made ahead of time, cool to room temperature, then cover and refrigerate. Reheat before serving.
To serve, spoon the kale mixture into warm bowls or plates, then top with a piece of walnut-crusted salmon.