1. Preheat Your Oven and Prepare the Pan: Start by preheating your oven to 400 F (200 C). Line a large baking sheet with parchment paper for easy cleanup. This step is crucial for preventing sticking and making post-dinner tidying effortless.

2. Chop the Ingredients: Cut your chicken breasts or thighs into uniform 1-inch pieces. Peel and cube your sweet potatoes into similar 1-inch pieces. If using, cut the red onion into wedges. Uniform pieces ensure everything cooks evenly at the same rate.

3. Season Everything Together: In a large bowl, combine the chicken, sweet potatoes, and red onion (if using). Drizzle with olive oil. Sprinkle with smoked paprika, garlic powder, onion powder, dried thyme, salt, and black pepper. Toss everything thoroughly until all ingredients are well coated with the oil and seasonings.

4. Arrange on the Sheet Pan: Spread the seasoned chicken and sweet potatoes in a single layer on the prepared baking sheet. Ensure there’s enough space between the pieces so they roast rather than steam. Overcrowding the pan can lead to soggy results. If necessary, use two baking sheets.

5. Roast to Perfection: Place the baking sheet in the preheated oven and roast for 25-30 minutes. Halfway through the cooking time (around 12-15 minutes), carefully remove the pan from the oven and toss the ingredients to promote even browning and cooking.

6. Check for Doneness: The chicken should be cooked through, with no pink inside, and reach an internal temperature of 165 F (74 C). The sweet potatoes should be tender when pierced with a fork and slightly caramelized at the edges.

7. Garnish and Serve: Once cooked, remove the sheet pan from the oven. If desired, sprinkle with fresh chopped parsley for a burst of color and freshness. Serve immediately and enjoy your easy, delicious meal.