Ready In: 45 m
- Preheat oven to 325 F degrees.
- In a skillet add 2 tablespoons of butter and melt it over medium heat.
- After the butter has melted, add the sliced onions. Now you have to cook the onions for about 20 minutes.
- To the onions, add the chopped mushroom stems.
- Add some salt and pepper, the white wine and the Worcestershire sauce. You’ll now need to let it cook for another 5 minutes or so, so that the liquid cooks down.
- In another large skillet that is oven proof, melt a little bit more butter, about a tablespoon and add the mushrooms. You can sprinkle some salt and pepper over them.
- Cook them for a couple minutes on each side. Spoon the onion filling in each mushrooms, about a tablespoon in each.
- Top each mushroom with Gruyere cheese.
- Bake the mushrooms for about 10 to 15 minutes at 325 F degrees or until the cheese has melted nicely and is golden brown.