1. Bring a large pot of salted water to a boil. Add the chickpea pasta. Cook until desired firmness, about 8 to 9 minutes. Strain and reserve 1/4 cup of the cooking liquid. Set pasta aside.
2. In a medium skillet, heat the oil and anchovy paste over medium heat. Add the leeks and shallots along with a pinch of salt. Cook for about 5 to 6 minutes, or until leeks start to soften. Add the garlic and cook for one minute.
3. Add the parsley and lemon juice and cook until lemon juice starts to evaporate, about 2 minutes.
4. Stir in the pasta. Add the reserved pasta water, one tablespoon at a time, as needed to loosen the pasta. Season with additional salt to taste. Add the salmon, using a wooden spoon to break the salmon up a bit.
5. Use a mini food processor to process the walnuts into “crumbs”.
6. Divide pasta onto four serving plates and top each serving with walnut “crumbs” and crushed red pepper, to taste (if using). Serve warm.