Prepare your Blackstone Griddle with a fresh bit of oil, if you are not sure How To Maintain Your Blackstone Griddle please check out this post -> here. Mine is always ready to go after it's been used making for little to no prep work.
Butter one side of your slice of Texas Toast, you will need two slices per sandwich, you can also mix in a bit of horseradish to give it a bit of a kick.
Slice up or tear up your prime rib, I used rarer pieces as I knew it would cook some in the process.
If your prime was in the fridge then microwave it for about 30 seconds or warm it up in a pan to make sure it will be warm after cooking your sandwich.
Spread your meat onto the bread.
Top with sliced or shredded cheese I used Havarti cheese slices, and it turned out amazing!
Place your second piece of bread and be ready to grill up the grilled cheese.
Fire up your Blackstone griddle onto a low-medium heat, or a pan on the stovetop.
Once your griddle is warm carefully place the assembled sandwich onto the griddle, or in the pan.
Allow continuing to cook until the bottom slice is starting to brown and flip the whole sandwich.
After I flipped mine I covered it with my Jim Bim Melting Dome to allow the cheese to melt. (If you don't have a melting dome Amazon has a great collection ->here)
Remove and serve!