Pat chicken thighs very dry with paper towels. Season generously with salt and pepper on both sides (his helps draw out moisture and crisp the skin). Place in the fridge uncovered for 30–60 minutes if you have time
Preheat the oven to 425 degrees and arrange the rack of your oven in the center. Make the cider glaze. In a small saucepan, combine the apple cider, garlic cloves, dijon mustard, apple cider vinegar, and maple syrup. Bring to a boil, then reduce heat to a simmer and cook for 10 minutes or until sauce is reduced and thickened slightly. Set aside to cool.
Add the chopped veggies and apple to a large sheet pan. Toss with olive oil to coat, add a bit of salt and pepper. Nestle the chicken on top of the veggies, skin side up.
Transfer to the oven and roast for 20 minutes. At the 20 minute mark, brush the chicken with some of the cider glaze and bump up the temperature to 450. Cook for another 15-20 minutes, or until skin is browned and crispy and the chicken internal temperature reaches 165F.
Drizzle the remaining cider glaze over the chicken and veggies to serve and garnish with optional thyme or rosemary.