Bring a large pot of salted water to a boil. Cook the spaghetti according to package instructions until al dente. Reserve 1/2 cup of the pasta cooking water before draining.

While the pasta cooks, heat the olive oil in a large skillet over medium heat.

Add the diced chorizo to the skillet and cook for about 4-5 minutes until it releases its oils and becomes slightly crispy.

Add the chopped onion to the pan and sauté for another 5 minutes until softened. Stir in the minced garlic and smoked paprika, cooking for 1 minute until fragrant.

Pour in the crushed tomatoes and bring the mixture to a gentle simmer. Let it cook for 5-7 minutes to thicken slightly.

Stir in the sliced green olives and season the sauce with salt and black pepper to taste.

Add the drained spaghetti directly to the skillet. Toss well to coat the noodles in the sauce, adding a splash of the reserved pasta water if the sauce is too thick.

Remove from heat and stir in half of the grated Manchego cheese and half of the parsley.

Serve immediately, garnished with the remaining cheese and parsley.