Season the chicken breasts with salt and black pepper. Chop the onion and mince the garlic. Drain and chop the pepperoncini, reserving juice.

In a large skillet, heat olive oil over medium-high heat. Brown the chicken on all sides for 5-7 minutes until cooked through, then set aside.

In the same skillet, add chopped onion and sauté for about 5 minutes until translucent. Add minced garlic and cook for 1 more minute.

Pour in the reserved pepperoncini juice, add chopped peppers, chicken broth, Italian seasoning, and red pepper flakes. Simmer for 5 minutes.

Let the sauce simmer for another 5 minutes, stirring occasionally, until thickened and aromatic.

Stir in heavy cream and return the chicken to the skillet, letting it soak in the sauce for 5 more minutes.

Mix everything well and adjust seasoning with salt and black pepper to taste.

Serve hot, garnished with chopped parsley, over cooked pasta or rice.