Prepare the dried porcini mushrooms according to the packaging. Usually, you are supposed to let them soak in slightly warm water for at leats 15 minutes, then boil them for another minute before they're ready to be added to your dish.
Heat up your veggie stock in a small pot. Set your big pot on medium-high heat, add olive oil.Chop your onion up finely, add it to your pot. Stir occasionally until the onion becomes translucent. Add your rice until it becomes slightly translucent as well. Be careful to stir often after you add your rice, otherwise it will stick ! In the meantime, cut your button mushrooms. You can cut them as you like, I usually do slices or big chunks in order to be able to really feel their texture. Add them to your bug pot as well.
Once the button mushrooms have reduced in size and the rice is part translucent, add the dry white wine, stir well and let it reduce. Add your dried or fresh thyme.
Start adding your stock to the rice one ladle at a time. You should barely have any liquid with your rice before starting to add more. Continue adding stock & stirring your rice continuously until you run out.
In parallel, you can chop your garlic cloves and add them to a small pan with some olive oil and your porcini mushrooms. Sauté them together for a few minutes before adding them to your rice. This step is optional, but I believe it gives more flavour to your risotto.Try adding your porcini mushrooms to the mix while you still have some stock left, in order to let them simmer with the rice and other mushrooms for a bit longer. Once you're out of stock, check if the rice is al dente : not too soft, but doesn't have a tough bite either. Is your rice is not cooked and you're out of stock, no worries ! You can just add some water to continue the cooking process. If your rice is perfectly cooked, cut the heat and start adding your parmesan. Mix it well. Season to your taste, although I would not recommend adding salt since the veggie stock & the parmesan are already salty. At the end you can add two small pieces of butter to give your risotto a nice shine. Serve with some more parmesan and enjoy !