On a plate, combine the flour with salt and pepper.
Coat each chicken breast in the flour mixture, pressing to adhere, and set aside.
Cook the linguine according to package instructions until al dente, drain, and keep warm.
In a large skillet over medium heat, heat the olive oil and butter until the butter is melted and shimmering.
Fry the floured chicken breasts 3–4 minutes per side, until golden; remove and set aside.
Add the minced garlic and onion powder to the skillet and cook 30–60 seconds until fragrant.
Pour in the chicken stock and cook 2–3 minutes, scraping any browned bits from the pan.
Add the crushed tomatoes and sugar, season with salt and pepper to taste, and simmer on low for 25–30 minutes.
With about 5 minutes remaining, stir in the chopped parsley.
Return the fried chicken to the sauce, top each breast with grated Parmesan, cover, and cook until the cheese is melted and the chicken is cooked through.
Serve the linguine topped with sauce and place a chicken breast over each portion; sprinkle additional parsley and Parmesan if desired.
