Cut the chicken into bite-sized pieces and toss with paprika, garlic powder, and sea salt until evenly coated.
Bring a large pot of water to a rolling boil and generously season with salt.
Heat 1 tablespoon olive oil in a large skillet over high heat. Add the seasoned chicken and cook, stirring occasionally, until cooked through and lightly browned, about 4–5 minutes. Remove chicken and set aside.
Reduce heat to medium and add the remaining 1 tablespoon olive oil and 1 tablespoon butter to the same skillet. Add the diced onion, minced garlic, and red pepper flakes and cook until the onion is softened, about 3–4 minutes.
Add the diced tomatoes to the skillet, season lightly with salt, and cook for about 5 minutes to combine flavors.
While the tomatoes cook, add the angel hair pasta to the boiling water and cook according to package directions, usually 4–5 minutes, until al dente. Reserve about 1/2 cup pasta cooking water, then drain the pasta.
Lower the skillet heat to low and stir in the heavy cream and grated Parmesan. Bring to a gentle simmer until the cheese melts and the sauce thickens slightly.
Return the cooked chicken to the skillet and stir to combine, heating through. Taste and adjust salt if needed.
Add the cooked angel hair and chopped parsley to the sauce and gently toss to coat, adding reserved pasta water a splash at a time if the sauce needs to be loosened. Serve immediately.
