Preheat and prep: Heat the oven to 425°F (220°C). Line a large sheet pan with parchment for easy cleanup.
Season the sprouts: Toss halved Brussels sprouts with 2 tablespoons olive oil, 1 minced garlic clove, 1/2 teaspoon salt, and 1/4 teaspoon black pepper.
Spread cut-side down on half the sheet pan for better caramelization.
Season the chicken: Pat the chicken dry. Drizzle with 1–2 tablespoons olive oil and season with 1 teaspoon kosher salt, 1/2 teaspoon black pepper, 1 teaspoon smoked paprika, and 1/2 teaspoon garlic powder. Add red pepper flakes if you like heat.
Zest half the lemon over the chicken.
Arrange on the pan: Place the chicken on the other half of the sheet pan. If using bone-in pieces, give them a little extra space for even browning.
Roast: Bake for 18–22 minutes for boneless thighs or breasts, 25–35 minutes for bone-in pieces. Stir the sprouts halfway through to brown both sides.
Check doneness: The chicken should reach an internal temperature of 165°F (74°C).
The sprouts should be tender with browned edges.
Finish with brightness: Squeeze the lemon over everything. If you want a touch of sweetness, drizzle 1–2 teaspoons honey over the sprouts and toss. Add chopped herbs and a sprinkle of Parmesan if desired.
Rest and serve: Let the chicken rest for 5 minutes.
Serve with the roasted sprouts and any pan juices spooned over the top.