Preheat oven to 350 degrees F. Lightly grease a large casserole dish; set aside.
In a large saucepan set over medium-high heat, combine the wild rice, vegetable broth and salt. Bring to a boil. Reduce heat to low, cover and simmer until the rice is tender, about 25 to 30 minutes. Stir in the quinoa, cover and cook an additional 15 minutes. Remove cover and cook an additional 5 minutes. Remove from heat.
While the rice is cooking, heat the oil in a large nonstick skillet over medium heat. Add the garlic and stir until fragrant, about 30 seconds. Add the onion and cook, stirring occasionally for 3 minutes. Add the celery and apple and continue stirring until soft, about 3 additional minutes. Add the fresh thyme and stir until combined. Add the greens and stir until wilted, about 1 to 2 minutes. Remove from heat. Stir in the cranberries.
Once the rice is done cooking, stir in the apple, cranberry and greens mixture into the rice.
Gently spoon the rice mixture into the casserole dish. Bake until golden brown, about 25 to 30 minutes. Garnish with fresh sage leaves. Serve immediately.