This recipe borrows a trick from Thomas Keller, who mixes in softly beaten heavy whipping cream at the very end for a super luxurious risotto.
Melt the butter in a sauté pan over medium heat until foaming. Add the mushrooms, thyme, and parsley, and cook to soften. Season with salt and pepper, to taste.
In a medium-sized pot, bring the chicken broth to a simmer over medium heat. Meanwhile, in place the heavy whipping cream in a mixing bowl and beat using an electric mixer or by hand until soft peaks form (the cream should just curl over softly when the whisk is held up).
Then, melt 2 tablespoons of the butter in a large pot. When it foams, add the onion and cook until translucent.
Then, add the rice and mix vigorously for about 1 minute. Add the white wine and let the wine soak into the rice until evaporated. Stir vigorously, scraping the bottom so the rice doesn't stick, until the rice has toasted, about 2 minutes.
Add enough chicken broth to cover the rice and cook, stirring frequently. When the rice has soaked up the broth (take a spoon and run it through; if the broth doesn't pool, it is ready), add another ½ cup of broth. Stir frequently until it has soaked in. Repeat with ½ cup increments until the rice is al dente.
Once the rice is ready (there should be a bite, but the center should be cooked through), remove from the heat and vigorously beat in the remaining butter, about 1-2 tablespoons at a time, with a wooden spoon. Beat in all of the cheese and 1/2 of the cream.
Taste, and if it's not creamy enough, add the remaining cream. Season with salt, to taste, and pour into plates. Top with the mushroom topping and garnish with parsley.