To prepare the stock:
Wash all the vegetables. Peel the carrots and cut them into 5-6 pieces, Peel onions and cut them into 3" chunks. Cut the celery into even sized big pieces 3-4".
Set a pot of cold water and place all the vegetables and bring it to a gentle simmer.
Once it starts simmering, skim and add the bay leaves, black pepper corns and a pinch of salt. (The salt brings out the flavors in the vegetables).
Simmer for 40-45 minutes and strain.
To make the risotto:
Bring 700 ml of water to a boil and soak the dried mushrooms for 15-20 minutes. Strain using a fine mesh strainer and add the water to the simmering stock. Wash the mushrooms under running water to get rid of any fine sand particles.
Remove the mushroom stubs wash and pop them into the simmering stock. Place them in a strainer add some all purpose flour and scrub them gently to remove any dirt, wash them thoroughly under running water.
Pat dry and quarter the mushroom into four. Chop garlic and cube the butter into 1 inch cubes.
In a heavy bottom pan (I prefer cast iron) heat olive oil over medium flame, add the chopped garlic and saute till slightly brown.
Add the porcini and saute till it is dry, continue adding the fresh mushrooms and keep stirring over high heat. (The moisture should be sealed inside) pop in a few lobes of butter and stir.
Lower the flame to medium and season with a touch of sea salt and pepper. Set the mushrooms aside in a plate.
Add the Arborio rice and keep stirring them till they are translucent, throw in the thyme sprigs and stir gently until you hear them scorch and release their aroma.
Ladle in the mushroom stock one at a time, till the rice is just submerged. Keep stirring once the stock dries out keep ladling the stock.
Keep tasting a few morsels of rice you will know when it is Al Dente, ladle more stock if required.
Stir in the mushrooms and finish with lobes of butter, parmesan and a dollop of Mascarpone. (Season only if required as Parmesan is a salty cheese)