Place the eggs in a pot and cover them with cold water. Bring the water to a boil over medium-high heat. Once boiling, cover the pot, remove it from heat, and let it sit for 12 minutes.

After 12 minutes, transfer the eggs to a bowl of ice water to cool for about 5 minutes. This will make peeling easier.

Peel the cooled eggs and chop them into small pieces.

In a mixing bowl, combine the chopped eggs, mayonnaise, Dijon mustard, chives, salt, black pepper, and paprika (if using). Mix until well combined.

Toast the slices of whole grain bread if desired.

Spread the egg salad mixture evenly onto two slices of bread. Top with lettuce leaves and tomato slices if using, then place the other two slices of bread on top to form sandwiches.

Cut the sandwiches in half and serve immediately.