Preheat your oven to 400°F (200°C). Spread the cubed sweet potatoes on a baking sheet, drizzle with a tablespoon of olive oil, and toss to coat evenly. Roast for about 25 minutes until they are tender and slightly caramelized, filling your kitchen with a sweet, toasty aroma.
While the sweet potatoes are roasting, heat a large skillet over medium heat. Add the remaining tablespoon of olive oil and once shimmering, sauté the minced garlic until fragrant—about 30 seconds—then add the chopped kale. Cook, stirring frequently, until wilted and bright green, about 3-4 minutes. Season with cumin, cinnamon, paprika, salt, and pepper for warmth and depth.
Remove the roasted sweet potatoes from the oven and transfer them to a large mixing bowl. Gently mash them with a fork or potato masher to break them into chunky pieces, while leaving some larger bits for texture.
Add the cooked kale and garlic mixture to the mashed sweet potatoes. Mix well to combine, ensuring the greens are evenly distributed throughout the sweet potatoes. This creates a colorful and hearty base for the casserole.
Transfer the mixture into a greased baking dish, spreading it out evenly with a spatula. Sprinkle the shredded cheese evenly over the top, covering the entire surface for a cheesy crust that melts beautifully during baking.
Bake in the preheated oven for 15-20 minutes, or until the cheese is melted, bubbly, and golden brown. The dish will emit a warm, cheesy aroma that invites everyone to dig in.
