Start with warming up the chicken stock (for vegetarian or vegan porcini risotto, use vegetable stock. It has to be hot by the time you mix it with the rice.
Cut up the dried mushrooms into pieces, smaller or bigger according to your taste and put them into a bowl. Pour hot or warm broth on it, enough to cover. Put the bowl aside, and let the mushroom soak up the broth.
Chop your onions and garlic finely.
In a large saucepan heat up the olive oil and half of the butter then add onions. Saute them on medium heat for about 3 minutes till they soften, then add garlic.
Add your rice. Stir and let it brown for approx. 2 minutes, until the edges of the grains become transparent. Stir occasionally.
Pour in the wine, stir and let the liquid evaporate for another half minute.
Pour in one or one and a half a ladle of hot stock. Stir the rice, then let it absorb the stock. Repeat.
You can add your mushrooms any time during the cooking process. Probably the best is to wait till the last couple of minutes. By doing so the mushrooms won't be overcooked and the dish will have an intense flavor. When you add the mushrooms pour the soaking liquid on the rice as well as it has already absorbed a lot of flavor of the mushrooms. Add salt and pepper to taste.
When the rice is cooked (cooking time depends on the type of risotto rice, usually 14 to 20 minutes, it is always indicated on the packaging), stir in the grated Parmesan cheese and take it off the heat.
Add remaining butter, stir, cover and let it sit for 2-3 minutes. Stir it once more and serve.