Season the chicken breasts with salt and black pepper on both sides.
In a large skillet, heat the olive oil over medium heat. Add the chicken breasts and cook for about 5-7 minutes on each side, or until they are golden brown and cooked through. Remove the chicken from the skillet and set aside.
In the same skillet, add the minced garlic and sauté for about 1 minute until fragrant.
Pour in the diced tomatoes (with their juice), oregano, basil, and red pepper flakes (if using). Stir to combine and let simmer for about 5 minutes.
Return the chicken to the skillet, spooning some of the tomato mixture over the top. Sprinkle the shredded mozzarella cheese evenly over the chicken. Cover the skillet and cook for an additional 3-5 minutes, or until the cheese is melted and bubbly.
While the chicken is cooking, prepare the dumplings according to package instructions.
Serve the chicken hot, garnished with fresh basil leaves if desired, alongside the dumplings.