Heat the broth in a small saucepan so that it is hot but not boiling
In a large skillet on medium high heat, melt 3 Tablespoons of butter, add in the shallots and one sprig of time, cook until shallots are translucent then add in the mushrooms.
Cook mixture until the mushrooms and shallots start to brown, then add in the garlic and season with a little bit of the salt and pepper. Once the mixture is nice and golden brown remove from heat and pour onto a plate. Set aside for later.
Return the pan to the heat, turn the stove down to medium heat and add in the remaining 3 Tablespoons of butter.
Once the butter is melted add the arborio rice and cook until the rice goes from white to translucent. This should take about 5 minutes. Turn the heat down if the rice begins to brown.
Pour in the white wine, lemon juice and remaining sprig of thyme. Bring the dish to a simmer stirring frequently. Once most of the liquid has been absorbed by the rice, add in 1 cup of the broth. Following the same process as the wine, stir frequently and wait until most of the broth has been absorbed before adding in another cup of the broth. Do this until the broth is gone and the rice is tender, but with a bite (al dente).
When you pour in the last ¼ cup of broth, add in the salt, pepper, and ½ of the mushroom mixture at the same time.
When the liquid has been absorbed, turn heat to low. Add in the heavy cream and freshly grated parmesan cheese. Cook this mixture for a few minutes until it is combined and the parmesan is melted.
Serve garnished with additional parmesan, fresh ground black pepper, the remaining mushrooms, and a roasted lemon slice.