Steps
1. In a small bowl, crack the eggs and whisk them together with salt and pepper.
2. Heat a non-stick skillet over medium heat and add butter. Once melted, pour in the eggs.
3. Stir the eggs gently until they scramble and are fully cooked, about 3-4 minutes.
4. While the eggs are cooking, toast the bread slices until golden brown.
5. Spread mustard on one side of each slice of toasted bread.
6. Place the cooked scrambled eggs on one slice of bread, add the cheese slice on top, and then cover with the other slice of bread.
7. Optionally, grill the sandwich on the skillet for an additional 1-2 minutes on each side until the cheese is melted and the bread is crispy.
8. Slice the sandwich in half and serve immediately.