Rinse and drain farro. Place in a pot with broth and salt and bring to boil. Reduce heat to a medium-low and simmer 30 minutes. Drain any excess water.
Meanwhile, heat olive oil in a large skillet. Add chicken and season with Italian seasoning and salt & pepper. Cook about 4-5 minutes or until chicken is mostly cooked through. Remove to a plate.
Add onion and garlic and cook until softened, about 2-3 minutes.
Return chicken to the skillet. Add marinara sauce, 1 cup water, kale, basil and balsamic vinegar and simmer on low until farro is finished cooking.
Stir in farro and 1/4 cup each of the Parmesan and mozzarella cheese.
Season to taste with salt and pepper. Sprinkle the remaining cheese on top. Remove skillet from heat, cover and let sit 2-3 minutes or until cheese is melted. Garnish with fresh chopped basil and red pepper flakes, if desired.