1. In a small bowl, combine garlic, lemon juice, and Dijon mustard. Let stand for 15 minutes, then whisk in the mayonnaise until smooth.
2. Taste and season with kosher salt and more lemon juice as needed.
3. To cook the bacon, preheat the oven to 400 F and line a large, rimmed baking sheet with parchment paper.
4. Place bacon in a single layer on the baking sheet, then put it in the oven on the lowest rack.
5. Cook for 15–20 minutes, or until browned and crisp to your liking.
6. Remove the bacon from the oven and transfer to a paper towel-lined plate.
7. While the bacon cooks, preheat a griddle or large pan over medium-high heat.
8. Spread butter on one side of each bread slice. Place the buttered side down on the griddle and toast until golden brown.
9. Remove toast from the griddle.
10. Spread the non-toasted sides with garlic aioli. Then top with bacon, tomato slices, and lettuce.
11. Serve whole or cut in half. Tip: Use cocktail picks to secure the sandwich until you’re ready to dig in.

*Cook Bacon to an internal temperature of 145 F (63 C) with a 3-minute rest.