Step 1

In a medium bowl, add tuna, avocado, salt, and pepper; mix using a fork until completely combined.

Step 2

Make your sandwiches: Place a slice of bread on the bottom and then layer cheese, tuna mixture, tomatoes, lettuce, and another slice of cheese. Top with remaining bread slices. Spread butter on outside slices of bread.

Step 3

Using a large skillet heated over medium heat; add sandwiches (butter side down), and cook for 3-4 minutes, or until bread is lightly browned. Flip and cook for 2-3 minutes or until bread is browned (usually the 2nd side takes a shorter amount of time to cook).

Step 4

Remove from skillet and let rest for 2-3 minutes. Using a serrated knife, slice the sandwiches down the middle and serve immediately.