Start by cleaning the mushrooms with a damp paper towel. Then, carefully remove the stems of the mushrooms and place the mushroom caps on a parchment paper-lined baking sheet.
Chop the stems and onions thinly and cook until tender and caramelized.
Pulse a piece of sourdough bread (or bread you have on hand) in a blender or food processor for a few seconds with the Stone House Seasoning.
Fill each of the mushroom caps with seasoned bread crumbs.
Then, top the mushrooms with the caramelized onions and mushroom stems.