Sheet Pan Lemon Chicken Thighs and Potatoes

0 Preheat oven to 425°F / 218°C. Line a sheet pan with foil. 
1 Pat chicken thighs dry with paper towels. Set aside. 
2 Whisk together all ingredients for dressing. 
3 Place potatoes and rosemary sprigs in a large mixing bowl and toss with one third of the dressing. Spread potatoes out on prepared sheet pan. 
4 Put chicken in mixing bowl and toss with one third of the dressing. Nestle chicken skin-side up in potatoes. 
5 Season the skin of the chicken thighs with some additional salt and pepper. 
6 Roast, stirring potatoes halfway through cooking, until potatoes are tender and chicken is cooked through and very crisp, 40 to 50 minutes. (Chicken is done when it registers 165°F in the thickest part.)
7 When chicken and potatoes are done roasting, drizzle with remaining one third of dressing. Garnish with a few fresh rosemary sprigs.
8 Serve immediately.