Preheat the oven to 400. Arrange the bacon slices on a rimmed baking sheet (line with parchment or foil for easier cleanup) and cook bacon until crisp and brown, about 15-18 minutes depending on thickness. Drain on paper towels.

In a food processor, blend the mayonnaise and basil until smooth.

Using a toaster or the broiler in your oven, toast the bread until lightly browned. Slather each slice with the basil mayo and top half the pieces with lettuce, sliced tomato (season with salt and pepper), and 3-4 pieces of bacon per sandwich. Top with the remaining bread and eat right away.