Prepare the mushrooms by wiping away any dirt with a wet cloth and removing the stems. Next, cut the mushrooms into large chunks.

Next, add the mushrooms along with the water, French onion soup, and butter to a pot.

Bring to a simmer over medium heat and cook until the liquid has reduced by half.

Next, add the heavy cream, black pepper, and a pinch of cayenne pepper to the other ingredients and continue to simmer until the sauce thickens.