In a large skillet, heat the olive oil and melt butter over medium-high heat. Add the chicken and cook for about 5-7 minutes on each side, or until it’s cooked through and golden brown. Remove the chicken from the skillet and set it aside.
To the same skillet add the minced garlic and cook for about 1 minute, or until it’s fragrant but not browned. Deglaze the pan with about ¼ cup of chicken stock, scraping up the brown bits from the pan with a spatula.
Then add the cream cheese to the skillet along with Dijon mustard, Italian seasoning, and another ¼ cup of the chicken stock. Stir until the cream cheese is mostly melted. Add the remaining chicken stock and stir well to combine all the ingredients.
Lower the heat and let the sauce simmer for about 2 minutes, or until it starts to thicken. Stir in the shredded parmesan cheese and let it melt into the sauce. If you like a little heat, add the optional red pepper flakes.