Kosher salt & freshly ground black pepper to taste
Spring pea shoots, for garnish
Melt butter in heavy, large skillet over medium-low heat. Add mushrooms, garlic, guanciale, and generous amount of pepper. Cook for about 5 minutes until mushrooms become juicy and guanciale starts to caramelize, stirring occasionally.
Meanwhile, cook pasta in large pot of boiling, salted water and drain.
Add cream and simmer until sauce thickens, about 4 minutes. Season with salt, then add Bel Paese cubes to sauce and stir until melted.
Add pasta to sauce and toss in peas. Top with Parmesan and garnish with pea shoots and generous amount of pepper.