1. Using the appropriate long and sturdy blade knife, which cuts from both sides, open the oysters. During this operation, stand over a saucepan to collect the water they contain.

2. Discard the flat valve and use a cloth to clean the edge of the valve containing the mollusk to remove any shell flakes. Keep 8 with the valve and remove the oyster from the others. Put these in the saucepan where you collected their water.

3. Gently sauté the chopped onion in a saucepan with half of the butter, add the rice, toast it for a moment, pour in the champagne and continue sautéing until it has all evaporated. Sprinkle with freshly ground white pepper.

4. Add a first ladle of boiling broth and, stirring constantly, add more ladles of broth, waiting for the risotto to absorb the previous one, and continue until the end of cooking.

5. In the last 5 minutes, gradually add the oysters with their water.

6. Only when cooked, mix the remaining butter cut into small pieces into the risotto. Give it a good stir and let it rest covered for a few minutes.

7. Pour it onto a warm serving plate forming a pyramid and place the oysters with the shell on top.

8. It must be served with champagne.