Preheat oven and brown chicken: Preheat oven to 400°F. Heat oil in a large oven-safe skillet over medium-high. Sprinkle chicken with ½ teaspoon salt. Cook chicken in skillet until golden brown on both sides and a thermometer inserted in thickest part reads 150°F, 5 to 6 minutes per side. (Chicken will not be cooked through.) Transfer to a plate.
Make the sauce in the skillet: Add broth and tomatoes to skillet; cook, scraping any browned bits from bottom of skillet, until tomatoes are softened and liquid is slightly thickened, about 3 minutes. Reduce heat to low. Add cream and harissa; cook, stirring often, until slightly thickened and creamy, about 2 minutes.
Return chicken to skillet and bake: Return chicken to skillet. Spoon some sauce over chicken and sprinkle with ½ cup feta. Bake until a thermometer inserted in thickest part of chicken reads 160°F, 10 to 12 minutes.
Cook sweet potato fries: While chicken bakes, cook sweet potato fries according to package directions. Sprinkle fries with remaining ¼ teaspoon salt.
Serve chicken with sauce, fries, and parsley: Transfer chicken to plates. Stir sauce. Top chicken with sauce and remaining ½ cup feta. Serve with fries, topped with parsley.
