Bring a large pot of water to a boil and add a splash of soy sauce. Add the spaghetti and cook according to the package instructions until al dente. Before draining, reserve some pasta water. Add the roasted nori sheets and sesame seeds to a blender. Blend until finely crushed.

Transfer the crushed seaweed mixture to a large bowl. Add the egg yolk, soy sauce, sesame oil, Parmesan cheese, and a splash of reserved pasta water. Mix until smooth and creamy.

Add the hot, drained spaghetti to the seaweed sauce. Toss well until the noodles are evenly coated. Gradually add more reserved pasta water as needed to create a silky sauce.

Heat chili oil in a pan over medium heat. Add the shrimp and cook for 2–3 minutes per side, or until pink and fully cooked.

Plate the seaweed pasta and top with the cooked shrimp. Finish with extra Parmesan cheese, sesame seeds, or chili oil if desired.