Bring broth to a boil in a small saucepan then add quinoa, place a lid on top, turn heat down to medium and then cook until quinoa is tender, 15-20 minutes. Fluff with a fork then set aside to cool slightly.
Meanwhile, heat extra virgin olive oil in a large skillet over medium heat. Add mushrooms and shallots then saute until tender, 5-7 minutes. Add garlic, season with salt and pepper, and then saute for one more minute. Set aside to cool slightly.
Add remaining ingredients to a large bowl with cooled quinoa and mushroom mixture then stir to combine. Line a large plate or platter with plastic wrap then shape 1/4 of the mixture into a patty and place onto platter. Mixture will be slightly wet - it's ok! Repeat with remaining mixture then refrigerate until completely chilled, 30 minutes or overnight.
Preheat oven to 375 degrees then line a baking sheet with foil and spray very well with nonstick spray. Transfer patties to baking sheet then spray tops with nonstick spray and bake for 14 minutes. Flip, spray tops with nonstick spray and then bake for 14-16 more minutes, or until the centers of the patties are set. Serve with buns and fresh condiments.
Notes
To freeze: wrap baked then cooled burgers in plastic wrap then freeze. To reheat, unwrap from plastic wrap then place on a plate and cover with a paper towel. Microwave for 1 minute on 50% power then 30-45 seconds on full power.