Fry the Steak: After frying a steak, Remove Steak. Reserve the steak juices in the pan, it will form the base of the sauce. Set aside.
Prepare the ingredients: Measure out the Dijon mustard, Heavy cream, Parmesan cheese and Butter.
Create the Sauce: Add the Heavy cream, Parmesan cheese and Dijon mustard to the saucepan with the steak juice and whisk until well combined. Place the saucepan over medium heat and bring the mixture to a gentle simmer, stirring occasionally. Stir the sauce frequently until it thickens, about two to three minutes. Transfer the sauce onto your steak.