Wash the mushrooms well with running water and cut them into ½ inch thick slices.
In a large skillet, add the olive oil and butter over medium heat.
Once hot, add the mushrooms and garlic powder.
Sauté the mushrooms with lid on, stirring occasionally, until they start releasing liquid (about 10 min)
Then, remove lid and let them finish cooking until soft.
Remove from heat, add green onions, remove portion without salt and pepper for baby (if <12m old).
Season with salt and pepper for the rest of the family and serve!