Prepare the couscous in a bowl according to package instruction, then break it up with a fork and dress with a drizzle of olive oil, salt and pepper.
Let the couscous cool, add the grated Grana Padano cheese, garlic, chopped parsley, and mix well.
Top each scallop shells with the couscous. Arrange the scallops on a baking sheet lined with parchment paper and bake in a preheated oven at 200 °C for 10-15 minutes, until golden.
Serve the scallops au gratin while still warm.