Bring a large pot of salted water to a boil. Cook spaghetti until al dente, about 8–10 minutes. Drain and set aside.

Heat olive oil in a large skillet over medium heat. Season chicken with paprika, Italian seasoning, salt, and black pepper. Cook for 5–7 minutes, turning occasionally, until golden brown and fully cooked. Remove and set aside.

In the same skillet, melt the butter. Add onion and sauté for 3–4 minutes until soft and translucent. Stir in garlic and cook 30 seconds until fragrant.

Pour in chicken broth and heavy cream. Stir gently, bring to a simmer, then reduce heat and cook 5 minutes until slightly thickened. The sauce should coat the back of a spoon.

Add spaghetti and chicken back into the skillet. Toss until pasta is well coated.

Sprinkle Monterey Jack cheese evenly over the pasta. Cover for 2–3 minutes until the cheese melts into a creamy layer.

Garnish with parsley and serve warm.