01 - Bring vegetable broth to a boil in a medium saucepan. Add quinoa, reduce heat to low, cover, and simmer for 15 minutes until liquid is absorbed. Remove from heat and let sit covered for 5 minutes. Fluff with a fork.
02 - Heat olive oil in a large skillet over medium-high heat. Add onion and sauté until translucent, about 3 minutes.
03 - Add minced garlic and cook for 1 minute until fragrant.
04 - Stir in sliced mushrooms and cook, stirring occasionally, until golden and their liquid has evaporated, about 7 minutes.
05 - Add dried thyme, salt, and pepper. If using, stir in spinach and cook until just wilted, 1-2 minutes.
06 - Add cooked quinoa to the skillet. Drizzle with lemon juice and toss everything together until well combined and heated through.
07 - Remove from heat. Stir in fresh parsley.
08 - Serve hot, garnished with grated Parmesan or vegan cheese and extra parsley if desired.