Preheat your oven to 400°F (200°C). Pierce each sweet potato a few times with a fork, then place them on a baking sheet. Bake for about 45 minutes until they are soft and the skin is slightly crispy.
While the sweet potatoes bake, rinse the quinoa under cold water using a fine sieve, then combine it with water in a saucepan. Bring to a boil over medium-high heat, then reduce heat to low, cover, and simmer for 15 minutes until the liquid is absorbed and the quinoa is fluffy.
Meanwhile, heat one tablespoon of olive oil in a skillet over medium heat. Add the minced garlic and sauté for about 30 seconds until fragrant. Add the chopped kale, season with salt and pepper, and cook until wilted and tender, about 5 minutes. Set aside.
Once the sweet potatoes are baked and cool enough to handle, carefully slice each open lengthwise and gently scoop out some of the flesh to create a cavity, leaving a border to keep the shape intact.
Fluff the cooked quinoa with a fork to loosen the grains. Mix half of the sautéed kale into the quinoa, along with a drizzle of olive oil and season with salt and pepper to taste.
Spoon the quinoa and kale mixture into the hollowed-out sweet potato halves, packing gently to fill the cavity evenly.
Return the stuffed sweet potatoes to the oven and bake for an additional 10 minutes, allowing the flavors to meld and the tops to turn slightly crispy.
Remove from the oven, garnish with the remaining sautéed kale if desired, and serve warm, enjoying the aroma and colorful presentation.