Peel the Jerusalem artichokes and cut them into pieces.
Cook them in the chicken broth until tender (about 20 minutes).
Add the heavy cream and butter, then blend until smooth.
Season with salt and pepper and keep warm.
Preparing the Parmesan crumble
Preheat the oven to 180°C (gas mark 6).
In a bowl, combine the Parmesan cheese, flour, and butter cut into small pieces.
Work the mixture with your fingertips until it has a sandy texture.
Spread the crumble mixture onto a baking sheet lined with parchment paper.
Bake for 8–10 minutes, until the crumble is golden brown. Set aside.
Cooking the scallops and final assembly
Shortly before serving, warm your plates in the oven at 50°C, in the microwave (with a bowl of water), or in a plate warmer. This will ensure that the dish is piping hot for all your guests, since it needs to be plated individually.
Coarsely crush the hazelnuts in a mortar, then toast them for a few minutes in a skillet over low heat.
Once the oil-butter mixture is hot (but not smoking!), sear the scallops for 1 minute on each side, until they are golden brown but still tender on the inside.
Season with salt and pepper, then keep warm (covered) until ready to serve.
Spread the Jerusalem artichoke cream over the bottom of each plate, then place the scallops in the center, and top them with the crumble and toasted hazelnuts. Serve piping hot!
Notes
For a splash of color, add a few fresh herbs (such as chervil or chives).
You can flavor the Jerusalem artichoke cream with a hint of truffle or a drizzle of hazelnut oil.