On a plate, place sliced sausage; set aside.
On a clean surface or serving tray, arrange crackers in two rows of twelve. Spread 1/2 to 1 teaspoon of mustard on half of the crackers; set aside.
On a medium-hot grill, place sausage slices, grill for 2 to 3 minutes or until slices begin to curl and edges begin to brown. Turn slices and center one piece of cheese onto each sausage slice. Cover. Grill an additional 1 to 2 minutes or until cheese begins to melt. Remove from grill and assemble s’mores. Serve immediately.