Fry the onion in a little olive oil until soft. Add the mushrooms and fry until golden brown. Season with freshly ground salt and black pepper. Add garlic, fry for another minute then remove from heat.
Heat a saucepan over medium-high heat, then add the butter. Once the butter has melted and is starting to brown, add the sage. Fry the sage until crispy and the butter is almost (just almost) burnt. Remove from heat and add the mushroom mix to the sage butter.
Use the same pan you did the mushrooms in, add a little olive oil with butter and fry the chicken pieces. Season with salt and black pepper, then once brown, add the wine. Let that reduce, about 5 minutes, then add the mushroom and sage mix to the chicken.
Stir in the cream and simmer for about 5 minutes.
Cook the pasta according to the package instructions. Before draining, add ½ a cup of the pasta water to the chicken and mushrooms.
Drain pasta and add to the chicken and mushrooms. Check seasoning and adjust if needed.
Serve with a generous amount of Parmigiano Reggiano and garnish with fresh sage leaves. Enjoy!