Place half of the mushrooms in a food processor and pulse several times to mince. Place a large skillet over medium-high heat and add the olive oil, then scrape the mushrooms into the hot pan. Add the remaining mushrooms to the food processor and mince, then add to the pan. Stir, scrAping the bottom of the pan, until the mushrooms are sizzling and give up their liquids. Add the Worcestershire sauce, salt and pepper and reduce the heat to a medium. Stir until the pan is dry, about 5 minutes. Transfer to a large bowl and let cool.