Preheat oven to 350 degrees F.

Blend walnuts and oats together in a food processor until they resemble breadcrumbs. Set aside in a large bowl.

Rough chop mushrooms and add to a food processor. Pulse until the mushrooms are broken down into ground pieces, but not turned into a paste. Set mushrooms aside.

Heat olive oil in a large skillet over medium-high heat. Add onion and garlic and cook for 1 to 2 minutes, until onions begin to soften. Add mushrooms and continue cooking for about 8 to 10 minutes, stirring occasionally.

Carefully add the cooked mixture back into the food processor and pulse a few times to combine the onion and mushrooms. Don’t over mix, as you still want visible pieces of the ingredients.

Add all of the spices and nutritional yeast into the walnut and oat mixture, then fold in the onion and mushrooms until combined. Taste and adjust seasoning, as needed. Whisk an egg and stir it into the mix.

Use a scoop to form golf ball-sized mushroom meatballs and place about 2 inches apart on a pan that has been prepared with non-stick spray. Bake for 20 to 24 minutes and serve with your favorite red sauce.