Monte Cristo Sandwich (Ham Cheese French Toast)

Bahan-bahan (2 porsi)

• 4 slices bread of choice ((Note 1))
• 1 large egg or 2 small eggs
• 1 tbsp milk
• Salt
• 2 tsp mayonnaise ((I like whole egg mayo))
• 2 - 4 slices gruyere cheese ((or other grated or sliced melting cheese of choice))
• Ham or turkey (, sliced or shaved)
• 1 - 2 tbsp unsalted butter