Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper.

In a large bowl, combine the sweet potatoes with 2 tablespoons of olive oil, garlic powder, salt, and pepper. Toss until the sweet potatoes are evenly coated. Spread them out in a single layer on half of the prepared baking sheet.

In the same bowl, combine the chicken breasts with the remaining olive oil, maple syrup, apple cider vinegar, thyme, salt, and pepper. Toss to coat the chicken evenly.

Arrange the maple-glazed chicken breasts on the other half of the baking sheet, making sure they are not overlapping.

Place the baking sheet in the preheated oven and roast for 25-30 minutes, or until the chicken is cooked through and the sweet potatoes are tender. The chicken should reach an internal temperature of 165°F (75°C).

In a small skillet, melt the butter over medium heat. Add the chopped pecans and cook for 3-4 minutes, stirring frequently, until they are fragrant and slightly toasted. Remove from heat.

Once the chicken and sweet potatoes are done, remove them from the oven. Sprinkle the toasted pecans over the sweet potatoes.

Transfer the chicken and sweet potatoes to a serving platter. Garnish with freshly chopped parsley before serving.