Prepare the Chicken and Aromatics: Pat the chicken cubes dry with paper towels and season generously with salt and pepper. Chop the onion into small, even pieces and mince the garlic. Drain the pepperoncini peppers, reserving 1/4 cup of the juice, and roughly chop the peppers.

Cook the Chicken: Heat the olive oil in a large skillet over medium-high heat. Add the seasoned chicken to the hot skillet in a single layer, avoiding overcrowding. Cook for about 5-7 minutes, or until the chicken is browned on all sides and cooked through (internal temperature should reach 165°F/74°C). Remove the chicken from the skillet and set aside.

Sauté Aromatics: Reduce the heat to medium. Add the chopped onion to the skillet and cook for about 5 minutes, or until softened and translucent. Add the minced garlic and cook for another minute, or until fragrant.

Create the Sauce: Pour in the reserved pepperoncini juice and scrape up any browned bits from the bottom of the skillet. Add the chopped pepperoncini peppers, chicken broth, Italian seasoning, and red pepper flakes to the skillet. Stir to combine.

Simmer and Thicken: Bring the mixture to a simmer and cook for about 5 minutes, allowing the flavors to meld together.

Add Cream and Chicken: Pour in the heavy cream and stir well. Reduce the heat to low and simmer for another 5 minutes, or until the sauce has thickened slightly.

Combine and Season: Return the cooked chicken to the skillet and stir to coat it in the sauce. Season with salt and pepper to taste.

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