Place the butter, two chopped cloves of garlic and the chopped shallot in a pan and fry slowly. In the meantime wash the prawns (remove the head and shells, cut prawns in half and wash well), add to the pan and brown. Then add the previously washed and cut mushrooms, add salt and pepper and cook for a few minutes. Add 800 ml broth and when it starts to boil add the rice and stir. Cook on a low flame for about 15 minutes. Once the rice has absorbed the broth, stir and add the remaining broth and some chopped parsley. Pour into a dish and serve.