Melt butter in a large skillet oven medium-low heat.
Add onions, mushroom and All Purpose Seasoning to the skillet and toss to combine.
Cook over medium-low heat for 30 minutes, stirring occasionally.
When onions and mushrooms are golden, remove from heat and serve immediately.
Notes
This Recipe Can be Doubled: This is a great recipe for a crowd. Simply increase the ingredients proportionately and split it into two baking dishes before baking.
Instant Pot: You can also make this recipe using an instant pot for quicker results. First cook the mushroom and onions on the pressure cook setting for 5 minutes. Then drain excess liquid and saute for an additional 3-5 minutes.
Quicker Prep Time: To reduce prep time, you can get pre-sliced mushrooms and onions or cut up ahead of time and store in the fridge.
Wine: Red Wine or White Wine adds to your favorite dishes.
Fresh Herbs: Fresh Parsley, thyme, black pepper or whatever you need.