Cook bacon according to package instructions.
Butter one side of each slice of bread. Sprinkle half the grated cheese on the non-buttered side of one of the pieces (or place 1 slice). Layer bacon, tomato and avocado and sprinkle remaining cheese on top.
Place the sandwich in a pan over medium heat, buttered side down. Top with the other slice of bread, buttered side facing up. Cover with a lid and cook for 2-3 minutes or until the bread on the bottom side is golden brown.
Carefully flip the sandwich to the other side and cook for 1-2 minutes or until the bread is golden brown and the cheese has melted.
Enjoy immediately!