Remove and discard the stems from the mushrooms.
Slice the mushrooms.
Heat the oil in a large, heavy skillet, add the mushrooms and garlic and sauté over high heat about 5 minutes, to sear the mushrooms.
Stir in the rice.
Cook, stirring, about 5 minutes until the rice is well coated with the butter and begins to whiten.
Have the stock barely simmering in another saucepan.
Add the wine to the rice, stir, then add 2 ladles of the hot stock.
Cook 3 minutes.
Stir in the mushrooms.
Continue adding stock, a couple of ladles at a time, stirring and adding more as the stock is absorbed by the rice.
Regulate the heat so the rice and stock cook at a steady simmer.
After about 15 minutes, the rice should have swelled and become somewhat tender but still a bit hard in the middle.
Continue adding stock for another few minutes, as needed until the rice is plump, offers only the slightest resistance to the bite, and there is just enough thickened, creamy, sauce-like broth to moisten the rice.
Stir in the remaining tablespoon of butter, season with salt and pepper, and serve with Parmesan cheese on the side.