Preheat oven on grill setting. Arrange bread slices in a single layer on a baking tray. Place under grill for 5 to 8 minutes or until lightly toasted on one side. Watch carefully to ensure they don't burn. Remove from oven and flip bread slices so that the toasted side is on the bottom.
Set the oven temperature for 180 degrees C.
In a small bowl mix together mayonnaise, pesto, garlic, Parmesan and salt. Spread evenly over untoasted sides of bread slices.
Bake in the preheated oven for 6 to 8 minutes. Set the oven to grill and place the rounds under the grill just until they begin to bubble and turn golden. Let cool slightly before serving.