Preheat oven on broiler setting. Arrange bread slices in a single layer on a cookie sheet. Place under broiler 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 350 degrees F (175 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 broil, and place the rounds under the broiler just until they begin to bubble and turn golden. Let cool slightly before serving.
