A double batch of homemade vegetarian ground meat substitute made with mushrooms and walnuts. Store in the freezer to have vegetarian ground beef on hand at all times!
Preheat the oven to 375ºF. Line a large baking sheet with parchment paper. Set aside.
Heat olive oil in a large skillet over medium heat.
Add the onion and both mushrooms. Cook, stirring frequently, until the mushrooms have released their liquid and most of the liquid has cooked off, 7-9 minutes.
Add the garlic and cook, stirring, for 1 minute.
Set the vegetables aside to cool for a few minutes.
Add the walnuts to the bowl of a food processor and pulse until they are the texture of a fine crumb.
Add the cooked vegetables to the food processor and let it run just until everything is very finely chopped.
In a large mixing bowl, add the walnut mixture along with the breadcrumbs, eggs, worcestershire sauce, onion powder, salt, and pepper. Mix thoroughly with a rubber scraper or big spoon until everything is incorporated.
Spread the mixture on the prepared baking sheet in an even layer.
Bake for 15 minutes, then remove from the oven and stir the mixture, flipping it over and breaking it up into smaller pieces. Spread it out evenly once again and return to the oven for another 15 minutes.