Soak porcini in boiling water for 10 minutes, reserve 5 Tbsp soaking liquid, and then finely chop mushrooms
Bring a pot of salted water to a boil and boil pasta until al dente, reserving 1¾ cups pasta water
In a cold large sauté pan, gently cook olive oil, garlic, red pepper flakes, parsley, and a pinch of salt over medium-low until soft, about 5 minutes
Increase heat, add mushrooms, tomato paste, and 50 cracks of black pepper, and cook 3 minutes
Return pan to medium-high, add 1½ cups pasta water plus porcini liquid, simmer 3 minutes
Stir in Parmesan until melted, followed by cream and drained pasta
Toss until emulsified, adding more pasta water if needed, and finish with olive oil, Parmesan, and parsley
