Heat the oven. Preheat to 425°F (220°C). Line a sheet pan with foil for easy cleanup and set a rack inside if you have one.
Dry the chicken. Pat the thighs very dry with paper towels.
This step is key for crispy skin.
Mix the seasoning. In a small bowl, combine salt, pepper, paprika, garlic powder, thyme, and rosemary. Zest the lemon into the bowl. Stir in the olive oil and honey to make a paste.
Season generously. Rub the paste all over the chicken thighs, especially under the skin where you can.
Place the thighs skin-side up on the prepared pan.
Add the veggies. Toss onion wedges, carrot chunks, and smashed garlic with a pinch of salt and a drizzle of oil. Scatter them around the chicken.
Roast. Bake for 35–45 minutes, until the skin is deeply golden and the thickest part of the thigh reaches 175°F (80°C). The vegetables should be tender and caramelized at the edges.
Finish with lemon. Squeeze the lemon juice over the chicken right out of the oven.
Let rest 5 minutes so the juices settle.
Make a quick gravy (optional but great). Transfer the chicken and veg to a platter. Place the pan on the stovetop over medium heat (or scrape drippings into a skillet). Add the stock and stir, scraping up any browned bits.
Simmer 3–5 minutes. For thicker gravy, whisk cornstarch or flour with a splash of cold water, then whisk into the pan. Finish with butter and adjust salt and pepper.
Serve. Spoon gravy over the chicken and veggies.
Sprinkle with chopped parsley for color.