Cut bread into 3/4-inch cubes. In a 10- by 15-inch baking pan, mix bread with 3 tablespoons oil, half of the garlic, and cheese.
Bake in a 375° oven until bread is golden, stirring occasionally, about 20 minutes. Let cool.
Cut bacon into 1/4-inch-wide strips. Stir bacon often in a 10- to 12-inch frying pan over medium heat until crisp, 6 to 8 minutes. Lift out bacon with a slotted spoon and drain on paper towels.
In a food processor or blender, whirl remaining garlic, balsamic vinegar, wine vinegar, and mustard, and with motor running, pour in remaining 1/2 cup oil.
Tear lettuce into bite-size pieces and place in a wide serving bowl.
Add croutons, bacon, and garlic dressing. Mix to coat greens. Add salt and pepper to taste.