Preheat your oven to 400°F and line a baking sheet with parchment paper.
Peel and cube the sweet potato into 1-inch pieces, then toss with avocado oil, a pinch of sea salt, and black pepper.
Spread the sweet potatoes on the baking sheet and roast for 20-25 minutes until tender and slightly caramelized.
While the potatoes roast, heat the ghee in a large skillet over medium heat.
Add the diced onion, minced garlic, and grated ginger, sautéing for 3-4 minutes until the onion is translucent.
Cut the chicken breast into bite-sized cubes and add them to the skillet, browning for 5 minutes.
Stir in the garam masala and turmeric, coating the chicken evenly with the spices.
Pour in the tomato puree and coconut milk, stirring to combine.
Lower the heat and simmer the sauce for 8-10 minutes until the chicken is cooked through and the sauce has thickened.
Season with the remaining sea salt and black pepper to taste.
Serve the creamy butter chicken directly over the roasted sweet potato cubes in a shallow bowl.