Heat a large sauté pan over medium heat and add bacon in an even layer.
Fry until crisp, about 5.
Transfer bacon using a slotted spoon onto a paper towel-lined plate and set aside.
Remove half the bacon fat and reserve.
Make croutons: Return pan to medium heat and toss bread in bacon fat; season with salt and pepper.
Toast until golden brown, about 5.
Transfer croutons to a bowl and set aside.
Add remaining bacon fat to sauté pan and toss with garlic over medium heat.
Sauté until garlic is softened and fragrant, 1 to 2.
Remove from heat and stir together with balsamic vinegar, salt, and pepper.
Add arugula, tomatoes, red onion, parsley, and croutons; toss together with dressing.
Top with bacon and basil and serve immediately.