Prepare ingredients: Lay out all ingredients on a clean surface.
Cook bologna: Heat a skillet over medium heat. Coat with cooking spray. Add bologna slices and cook for 2-3 minutes per side, or until crispy and golden brown.
Toast bread: While bologna is cooking, toast bread slices in a toaster or toaster oven.
Assemble sandwiches: Spread mayonnaise on one side of each toasted bread slice. Add cheese to two slices. Top with bologna and tomato. Place remaining bread slices on top, mayonnaise side down.
Cook sandwiches: Heat the same skillet over medium-low heat. Coat with cooking spray. Cook sandwiches for 2-3 minutes per side, or until cheese is melted and bread is golden brown.
Serve: Let sandwiches cool slightly before serving. Slice in half if desired. Enjoy!
