TIP: It’s Ok if not all of the peppercorns stick; you'll be able to add them to the pan sauce in the next step. TIP: Add a pinch of peppercorns now if they didn’t stick in step 3.) Simmer, flipping mushrooms sometimes, till sauce has thickened and mushrooms are coated, 1-2 minutes more. Step 2 - In a small saucepan, heat the cream until it virtually reaches a boiling point - but don't permit it to boil. Bring to a boil and cook till tender, 15-20 minutes. Just ensure you don’t cook them, as this may destroy the psychoactive substances.