Finely chop the spring onion and brown it with 50 gr. of butter, then add the pigeons, which you have previously cleaned, washed, cut into pieces and boned, and let them pass a little in the seasoning obtained with the addition of salt, pepper and nutmeg (if you want to season them further add some sausage).
After about 15 minutes of cooking, add the mushrooms (soaked in warm water) and the bay leaf: cook everything over low heat. If necessary, pour in a few tablespoons of broth. In the meantime, grease a high-sided mold with butter and sprinkle it with breadcrumbs: it will be the container of your bomb.
Cook the rice in abundant salted water until “al dente”, drain it, mix it with an egg and season it with the remaining butter and cheese. Pour half of the mixture obtained into the buttered form so as to leave space in the center, where you will place the pigeons with their sauce. Cover with the remaining rice and sprinkle the surface with breadcrumbs and butter flakes. Brown in a hot oven. When cooked, leave to rest for about 10 minutes and then turn out onto a serving plate and serve at table.