Preheat your oven to 375°F (190°C). Lightly grease an 8×8 inch baking dish.

In a medium saucepan, combine the rinsed quinoa, rinsed lentils, and 3 cups of vegetable broth. Bring to a boil, then reduce heat, cover, and simmer for 20 minutes, or until most liquid is absorbed and grains are tender. Drain any excess liquid.

While the grains cook, heat the olive oil in a skillet over medium heat. Add the onion and cook until softened, about 5 minutes. Add the garlic and cook for 1 minute more until fragrant.

In a large bowl, combine the cooked quinoa and lentil mixture, the cooked onion and garlic, the squeezed dry spinach, nutritional yeast, plant milk, thyme, salt, and pepper. Mix well until everything is evenly distributed. If the mixture seems too dry, add the extra 1/2 cup of vegetable broth.

Transfer the mixture to the prepared baking dish and spread it into an even layer.

Bake for 25 to 30 minutes, or until the top is lightly set and the casserole is heated through.

Let the casserole rest for 5 minutes before cutting and serving.