Spread butter on one side of each slice of bread. spread pepper jelly on the unbuttered sides of four slices of bread.
On slices of bread with pepper jelly, place two slices of Pepper Jack cheese and two pieces of grilled andouille sausage over the jelly. cover sausage with two slices of Muenster cheese and top with the remaining slices of bread, buttered side out.
Preheat a large skillet or griddle over medium heat.
Cook sandwiches for 2 to 3 minutes on each side, or until golden and the cheeses are melted.