Preheat oven to °375F.
Heat the chicken broth in a small saucepan until barely simmering.
Lightly cook the onion in 2 tablespoons butter over medium heat until translucent then add the rice, coating it until shiny for about 2 minutes.
Pour the wine over the rice and cook until absorbed completely.
Cook the rice, adding the chicken broth little by little and waiting between each addition until completely absorbed.
In the meantime, sprinkle a little bit of Fleur de Sel over the marrow bones and cook in the oven for 10 minutes, finishing them under the broiler for a few minutes.
Cook the fresh peas in salted boiling water for 10 minutes, then drain and lightly mash them.
Add the peas to the rice and stir to combine.
Once all the broth has been absorbed, add salt and pepper to taste and the grated parmesan while mixing well.
Add the rest of the butter, cut into small pieces, stirring well and serve with the marrow bones.
