Preheat the oven to 350°F (176°C) and place a rack in the middle position.
In a small saucepan combine 5 cloves garlic (peeled and lightly pounded), 1 tablespoon finely chopped parsley, 1/2 teaspoon salt (or to taste), and 1/4 cup olive oil. Warm over low heat and simmer gently for 3 minutes; watch carefully so the garlic does not burn.
Remove the pan from the heat and discard the garlic cloves.
Put the 4 pieces of bread (cut into 3/4-inch/2 cm cubes, about 6 cups) in a large bowl. Pour the cooled (or warm) oil-herb mixture over the bread and toss until the cubes are evenly coated.
Spread the coated bread cubes in a single layer on a parchment-lined baking sheet.
Bake on the middle rack for 8 minutes.
Remove the sheet from the oven and sprinkle 1/4 cup finely grated fresh Parmesan evenly over the croutons. Return to the oven and bake an additional 5 minutes, or until the croutons are golden and crisp.
Remove from the oven, taste and add a little extra salt if desired, then let the croutons cool completely on the baking sheet (they will crisp as they cool).
Store cooled croutons in an airtight container for up to 1 week. Serve as a topping for tossed green salad.