Preheat the oven to 400°F (200°C).

In a large bowl, combine olive oil, garlic powder, onion powder, smoked paprika, salt, pepper, and lemon zest. Add the chicken thighs and coat well, allowing them to marinate while you prepare the sweet potatoes.

In another bowl, toss the cubed sweet potatoes with olive oil, salt, and pepper until well coated.

On a large baking sheet, spread the sweet potatoes out in an even layer. Place the marinated chicken thighs directly on top of the sweet potatoes.

Place the baking sheet in the preheated oven and bake for 30-35 minutes, or until the chicken is cooked through (internal temperature should reach 165°F or 75°C) and the sweet potatoes are tender.

While the chicken and sweet potatoes are baking, prepare the tzatziki. In a mixing bowl, combine Greek yogurt, grated cucumber, lemon juice, minced garlic, dill, and a pinch of salt. Mix until well combined and refrigerate until ready to serve.

Once cooked, remove the baking sheet from the oven. Serve the chicken and sweet potatoes hot with a generous drizzle of tzatziki sauce over the top. Enjoy!