Sprinkle salt, black pepper, paprika, and oregano over the chopped chicken and mix to coat thoroughly.
Heat oil in a large frying pan over medium heat.
Cook the chicken for 5-6 minutes, turning often, until golden and cooked through. Remove and place in a bowl.
Add butter to the pan and melt, then add sliced onion and fry gently for 2-3 minutes until translucent, stirring often.
Add garlic and parsley, stir and cook for 1 minute.
Pour in chicken stock and bring to a simmer. Add spaghetti ensuring it is covered with liquid.
Cover the pan with a lid or foil and simmer gently for 10-12 minutes, stirring occasionally to prevent pasta sticking.
Stir in cream and parmesan, then add the cooked chicken back to the pan.
Cook for an additional 2-3 minutes, stirring occasionally, until chicken is heated through and sauce is creamy.
Divide pasta between bowls and top with grated parmesan, chopped parsley, and freshly ground black pepper before serving.