1) First of all, the oven needs to be preheated to 350 degree Fahrenheit.
2) The next step is to take a small oven proof frying pan.
3) Add olive oil and it should be heated.
4) Then, it is the time to add mushroom and it should be fried for 1 to 2 minutes on each side. (You can stop when the mushroom becomes golden brown)
5) It should be kept warm in the pan.
6) You need to take a small bowl and cheese and herbs must be added.
7) Garlic and butter should also be added and all these four ingredients need to be mashed in the bowl. (Make sure that they are all well combined)
8) Then, this mixture has to be used to stuff the mushroom.
9) The chopped onion has to be sprinkled over and the pan should be transferred to the oven.
10) It must be roasted for 5 to 6 minutes. (Make sure that the stuffing becomes golden brown and bubbling)
11) It can be transferred into s serving plate immediately.