1. Start by cooking the bacon: In a large skillet over medium heat, cook the bacon slices until they’re crisp but not overly crunchy, about 6-8 minutes, flipping halfway through. Drain on paper towels to remove excess grease. I always cook extra bacon when making this sandwich because, like my daughters, I can’t resist sneaking a slice or two!
2. While the bacon cooks, prepare your bread. Spread a thin layer of softened butter on one side of each slice. This will be the outside of your sandwich and will help create that golden, crispy crust that’s so satisfying.
3. In a small bowl, mix the mayonnaise with Dijon mustard, if using. Spread this mixture evenly on the unbuttered side of two bread slices. This adds a subtle tang and moisture, keeping the sandwich from feeling dry.
4. Layer on the cheese generously over the mayo-mustard side of the bread. Don’t be shy here; the cheese is what melts into that gooey, irresistible center.
5. Add the cooked bacon slices evenly over the cheese, then top with tomato slices. Sprinkle a pinch of salt and pepper over the tomatoes to enhance their natural sweetness—a little trick I learned from my time in Spain, where seasoning fresh produce is key.
6. Finish with fresh lettuce leaves, then place the remaining bread slices on top, buttered side facing out.
7. Heat a clean skillet or griddle over medium-low heat. Place the sandwiches in the pan and cook slowly for about 4-5 minutes per side, pressing gently with a spatula. You want the bread to toast evenly to a deep golden brown and the cheese to melt thoroughly without burning the outside.
8. Once golden and melty, remove the sandwiches and let them rest for a minute before slicing. This pause lets everything settle, making each bite perfectly balanced.

Pro tip: When I’m making this for my daughters, I sometimes cover the skillet briefly with a lid to trap heat and help the cheese melt faster without turning the bread too dark. It’s a little trick my mother used with similar sandwiches, and it really works!