Preheat oven to 400 degrees Fahrenheit and line a large baking sheet with parchment paper.
Peel and dice the sweet potato into half-inch cubes and halve the Brussels sprouts.
Place the sweet potato and Brussels sprouts on the baking sheet, drizzle with half the olive oil, and sprinkle with sea salt, black pepper, and cinnamon.
Toss the vegetables to coat evenly and spread them out in a single layer.
Cut the chicken breast into bite-sized pieces and season with garlic powder and the remaining sea salt and black pepper.
Move the vegetables to one side of the tray and add the chicken to the other side, drizzling with the remaining olive oil.
Roast for 20 to 25 minutes until the chicken is cooked through and the sweet potatoes are tender and golden.
While roasting, de-stem and chop the kale, then massage it in a bowl with the apple cider vinegar until slightly softened.
Divide the kale into bowls and top with the roasted chicken, sweet potatoes, and Brussels sprouts.