In a pot, heat extra virgin olive oil, butter and throw in sprig of nepitella. Add fresh porcini to the pot and let cook for a minute so that the mushrooms can absorb all the flavours.
Add a ladle of vegetable broth and allow porcini to cook for another minute or until the broth has been absorbed. Add salt and black pepper to season and pour in the remaining broth. Bring the soup to a boil and then lower the heat. Let simmer for half hour.
Before plating, add parmigiano cheese and 2 eggs. Stir very well for a minute and serve hot.