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 chopped onion and sauté until translucent, about 3 minutes.
03 - Stir in minced garlic and cook for 1 minute until fragrant.
04 - Add sliced mushrooms and cook, stirring occasionally, until golden and their liquid has evaporated, about 7 minutes.
05 - Add dried thyme, salt, and pepper. Stir in baby spinach and cook until just wilted, 1 to 2 minutes.
06 - Add cooked quinoa to the skillet. Drizzle with lemon juice and toss everything together until well combined and heated through. Remove from heat and stir in fresh parsley. Serve hot garnished with grated Parmesan and extra parsley if desired.