Heat the Oven - Set the oven rack in the center position. Preheat to 400°F (204ºC).
Make the Maple Dijon Sauce - In a small bowl, combine the Dijon mustard, maple syrup, and water. Set aside.
Prepare the Chicken - Trim the chicken thighs of excess fat and skin. Generously season both sides with salt, pepper, paprika, and garlic powder.
Sear the Chicken - Heat a large oven-proof skillet over medium-high heat and add 1 tablespoon olive oil. Once hot, add the chicken thighs, skin-side down. Sear until the skin is crispy, about 5 minutes, then flip the pieces. Turn off the heat. Carefully drain or use a paper towel to soak up the grease from the pan, leaving 2 tablespoons.
Add the Sauce - Move the chicken to the sides of the pan. Heat the skillet over medium heat. Add the garlic and saute for 30 seconds. Add the sauce and stir to combine.
Add the Potatoes - Add the sweet potatoes and coat with the sauce, simmer for 2 minutes. Season with salt and pepper. Add the rosemary sprigs around the pan, breaking them into smaller pieces if they are too long.
Roast - Transfer the skillet to the oven and roast for 30 minutes. Remove from the oven and discard the rosemary.
Roast the Beans - In a medium bowl, combine the green beans, 1 tablespoon olive oil, ½ teaspoon salt, and ¼ teaspoon black pepper. Scatter the green beans around the pan and roast in the oven until bright green and crisp, about 15 minutes.
To Serve - The sweet potatoes should be fork-tender, and the chicken thighs should reach about 170ºF (77ºC) on a meat thermometer. Add more cooking time as needed. Portion and serve with more sauce drizzled on top.
Notes
Mustard Substitution: Coarse ground mustard can be substituted with 2 tablespoons smooth Dijon mustard and 3 tablespoons wholegrain mustard. Alternatively, use all smooth Dijon.
Using Chicken Breasts: Cook until the internal temperature reaches 160 to 165ºF (71 to 74ºC).
Storing: Cool and store leftovers in an airtight container. Refrigerate for up to 3 days.