Begin by seasoning the boneless, skinless chicken breasts with salt and black pepper.

Chop the yellow onion finely and mince the garlic.

Drain the pepperoncini peppers, roughly chop them, and reserve 1/4 cup of the brine.

Heat olive oil in a skillet over medium-high heat. Add the seasoned chicken and cook until golden brown, about 5-7 minutes.

Transfer the chicken to a plate and set aside.

In the same skillet, add the chopped onion and cook until translucent, about 5 minutes. Then add the minced garlic.

Stir in the reserved pepperoncini juice, chopped pepperoncini, chicken broth, Italian seasoning, and red pepper flakes. Bring to a simmer.

Let the sauce simmer for about 5 minutes to thicken.

Stir in heavy cream and return the chicken to the skillet. Simmer for another 5 minutes.

Adjust seasoning with additional salt and black pepper if necessary.

Garnish with fresh parsley and serve hot over cooked pasta or rice.