Brush both sides of the steaks with melted butter. Season both sides liberally with salt and pepper, pressing them into the steak.
Place the steaks on the grill on a diagonal and cook until slightly charred. Turn the steaks over halfway through the designated time below. See the chart below for your desired temperature. (see notes for crosshatching look)
Medium-rare: 3 to 5 minutes each side (135 degrees F)
Medium: 5 to 7 minutes each side (140 degrees F)
Medium-well: 5 to 8 minutes the first side, 8 to 10 minutes on second side (150 degrees F)
As soon as you remove the steaks from the grill, wrap them in aluminum foil and let them rest for 15-20 minutes.
Note: You must let the steaks rest! Keeping them wrapped in foil will keep them warm.
Heat the butter in a medium to large pan over medium heat. As soon as the butter has melted, add the shrimp and season with salt and pepper. Stir to coat the shrimp on both sides.
Let the shrimp cook on one side for 1-2 minutes until it is firm. Turn the shrimp over and cook that side for another 1-2 minutes.
Add the garlic and stir. Let the garlic cook for about 1 minute.
Pour in the chicken stock and lemon juice and let it come to a slow boil. Reduce the liquid for 2 minutes.
Add in the Dijon mustard, whole grain mustard, and Cajun seasoning. Stir to mix it throughout the dish.
Next, add the half-and-half and Parmesan cheese. Stir until the cheese is dissolved. Cook for 3-4 minutes and allow the sauce to thicken.
You can serve the Cajun Shrimp over the steak or on the side. It is designed to be the sauce for the steak, but you can use your favorite steak sauce. Garnish with chopped fresh parsley.
Different Steak Thicknesses
What if your steaks are slightly thinner or thicker? For thinner steaks, use the lowest end of the chart above, and for thicker steaks, use the longer times mentioned above.
To create the beautiful crosshatch marks on steaks, think in terms of Northeast and Northwest, not the literal ones. As you look at your grill, North is straight ahead, East is on your right and West is on your left. I always start with Northeast so I always know which direction I started with, so I will use that for these instructions. I will also use a 5 minute cooking time per side.
You're done! And you should have those awesome crosshatch marks and everyone will think you're a Grill Master!