Start by heating a non-stick skillet over medium heat and add a tablespoon of butter, letting it melt until bubbling and fragrant.
Place the thick slices of bologna in the hot skillet, letting them sizzle and crisp up at the edges for about 2-3 minutes on each side, until golden brown and slightly crisp.
While the bologna fries, toast your bread slices until lightly golden, either in a toaster or by adding them to the skillet for 1-2 minutes, pressing down gently for extra crunch.
Once crispy, transfer the bologna slices to a paper towel-lined plate to drain excess fat, giving them a moment to stay crispy and juicy.
If using cheese, place a slice of cheddar on one of the hot bologna slices to melt slightly while still in the skillet.
Assemble the sandwich by layering the fried bologna (with optional cheese) on one slice of toasted bread, then add mustard or pickles if desired.
Top with the second slice of toasted bread, pressing down gently to help everything stay together.
Cut the sandwich in half if you like, and serve immediately while the bologna is crispy and the bread is warm.
