In a large skillet, heat the olive oil and butter over medium heat. Once melted and hot, add the chicken pieces. Season with salt and pepper. Cook until the chicken is browned and cooked through, about 5-7 minutes. Remove the chicken from the skillet and set aside.
In the same skillet, add the gnocchi and toast them for about 2-3 minutes until they start to turn golden brown.
Pour in the chicken broth and bring to a simmer. Allow it to cook for about 5 minutes, stirring occasionally, until the broth reduces slightly.
Stir in the marinara sauce and cooked chicken. Mix well and let it simmer for another 2-3 minutes until everything is heated through.
Remove the skillet from heat and stir in the grated Parmesan cheese until melted and creamy. Adjust seasoning with salt and pepper if needed.
Serve immediately, garnished with fresh basil or parsley if desired.