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