Add all ingredients except the steak to a bowl. There are 2 EXTREMELY important things here. 1. Make sure that the butter is as soft as it can be. Room temperature is great. 2. Make sure that the spinach is as dry as can be. Use fresh chopped spinach or if you are using frozen (like I did) make sure you squeeze as much of the moisture out of the vegetable as possible.
Using a fork combine all of the ingredients well.
Trim your beef of as much of the fat as you can. You can see there is a good bit of marbled fat in the meat. We are not concerned about that, what we are concerned about is the fat along the outside edges and the big pockets of fat that you can see I removed.
Insert a long, thin sharp knife into the meat. Swing the blade back and forth to make a big pocket in the steak while trying to keep the incision as small as you can.
Small Incision with a big pocket. That is what we are going for. We want as much of the stuffing to remain in the meat as possible.
Put as much of that stuffing into the steak as you can. Use a small spoon, a fork or your fingers. Don’t worry about getting it on the outside of the steak.
Coat the top of your steak with some of the remaining stuffing. Do not coat the whole steak, just the top side.
Place your steaks on a preheated grill coated side up. Make sure it is a high heat but no flames. Charcoal is best for the flavor but propane will work. Cook the meat approximately 3 minutes. Give the meat a quarter turn then cook on the same side for another 3 minutes.
Flip the steak and coat with the remainder of the stuffing. Repeat the process of cooking for 3 minutes and turning. This will give you a medium – medium rare steak. For a more well done steak cook 1-2 minutes more per side.
Remove the meat, tent with foil and let rest for 10 minutes.
Cut into individual servings.
We served with a side of baby red skinned garlic mashed potatoes. Because the meat was infused with butter it cut extremely easily and tasted absolutely delicious.