For the mushrooms
01 -
20 medium cremini or white button mushrooms, about 1 1/2 lb (680 g)
02 -
1 tablespoon olive oil, plus more for the pan if needed
03 -
1 tablespoon unsalted butter
For the sausage filling
04 -
1 lb (450 g) Italian sausage, casings removed if using links
05 -
1/2 small yellow onion, finely chopped
06 -
1/2 cup finely chopped mushroom stems
07 -
3 cloves garlic, minced
08 -
1/2 teaspoon dried oregano
09 -
1/2 teaspoon kosher salt, plus more to taste
10 -
1/4 teaspoon black pepper
11 -
6 oz (170 g) cream cheese, softened
12 -
3/4 cup (75 g) freshly grated Parmesan cheese, divided
13 -
1/4 cup (25 g) Italian breadcrumbs
14 -
2 tablespoons chopped fresh parsley, plus more for serving