Cut the chicken breast into small, even cubes and season lightly with a pinch of salt and pepper. Finely chop the onion and mince the garlic.

Bring a large pot of well-salted water to a boil. Add the tagliatelle and cook according to package directions until al dente. Reserve 2 tablespoons of cooking water, then drain the pasta.

While the pasta cooks, heat 1 tablespoon of olive oil in a large skillet over medium-high heat. Add the chicken and cook for 5 to 7 minutes, stirring occasionally, until golden and cooked through. Transfer the chicken to a plate, leaving any juices in the skillet.

Add the remaining 1 tablespoon of olive oil to the same skillet. Add the chopped onion and cook for 2 to 3 minutes over medium heat, stirring, until softened and translucent.

Add the minced garlic and cook for 30 to 60 seconds, stirring, until fragrant but not browned.

Sprinkle in the sweet paprika and cook for 1 minute, stirring constantly, to release its aroma without burning.

Pour in the heavy cream, scraping up any browned bits from the bottom of the skillet. Bring to a gentle simmer over low heat and cook for 3 to 4 minutes until slightly thickened.

Return the cooked chicken and any accumulated juices to the skillet. Stir to coat in the sauce, then taste and season with the remaining salt and pepper.

Add the drained tagliatelle to the skillet and toss over low heat until the pasta is evenly coated with the creamy paprika sauce. If the sauce seems too thick, stir in the reserved pasta water 1 tablespoon at a time.

Serve immediately, sprinkled with chopped fresh parsley.