Preheat large skillet over medium high heat. Add butter and allow to melt.
Fill an 8x8 baking dish (or other square dish) with enough grape juice to cover the matzah. Gently place matzah, one piece at a time, into the grape juice and lightly press down to cover it. Leave for about a minute, until it soaks up enough juice to turn colors.
Use a spatula to carefully remove matzah from grape juice and place in skillet. Top with whatever cheese you prefer (I like to use a combination of shredded cheddar and mozzarella).
Soak the second matzah cracker as you did the first one and top the grilled cheese.
After sandwich becomes lightly browned on the bottom, gently flip it over and brown the other side. Sometimes it breaks so you may prefer to just cut the sandwich into fourths with your spatula and flip each section individually.
Remove to a plate and serve. Best eaten with a fork.