Bring 5 cups broth to a boil in a large saucepan. Add quinoa, salt and pepper and return to a simmer. Cover, reduce heat to low to maintain a gentle simmer and cook until the quinoa is tender and the broth is absorbed, 18 to 22 minutes. Remove from heat and let sit undisturbed 5 minutes. Remove lid, stir in kale, cover and let sit.
Meanwhile, preheat oven to 350 degrees F.
Heat butter and oil in a large skillet over medium-high heat. Add onion and cook, stirring often until the onion is very soft and starting to brown, 7 to 9 minutes. Add garlic, sage, thyme and cinnamon and cook until fragrant, 30 to 90 seconds. Add celery and the remaining 1⁄2 cup broth, and cook, stirring often until the celery is crisp-tender and the liquid is mostly evaporated, 4 to 6 minutes.
Stir quinoa mixture, the celery mixture, walnuts and cranberries together in a large bowl. Transfer to a 9 by 13-inch baking dish coated with cooking spray.
Bake until the mixture is hot, the celery and kale are tender and the top is golden along the edges, 22 to 30 minutes.