Place a 7-inch (18-cm) nonstick skillet over medium heat.
Have a small bowl, 4 to 5 inches (10 to 13 cm) in diameter, ready on the counter. Turn the bowl upside down.
When the pan is moderately hot, pour ¼ cup (30g) of the cheese and quickly tip the pan to coat the bottom, as if making a crepe. Shake out any excess. Cook briefly until any little white bubbles have disappeared and the cheese begins to color around the edges.
Carefully lift up the layer of Parmesan and turn it over.
Cook it for a few seconds longer, then lift it out and place it briefly on the small overturned bowl to form it into a shell.
Allow it to cool a minute or so then gently lift it off.
Repeat with the remaining cheese to make 3 more shells.
Set aside at room temperature up to 2 hours, until ready to serve. The crisped cheese can also be cooled flat, then broken into large pieces to serve as a snack.