1. Mash beans, garlic, olive oil, salt and pepper with a fork and reserve.
2. Arrange 4 slices bread on a work surface. Spread 3 tablespoons white-bean mixture on each slice of bread.
3. Top with 2 slices lettuce and 2 tomato slices.
4. Layer another slice of bread on each sandwich and top with each with 4 slices avocado and 2 slices turkey bacon. Top with last piece of bread.
5. Slice sandwiches in half diagonally, and secure with toothpicks.