Preheat your oven to 375°F. While it heats, pat the chicken thighs dry with paper towels—this is crucial for achieving golden, crispy skin during roasting. Season the dried chicken generously with salt and pepper on both sides, making sure to coat the skin evenly. Cut the potatoes into 1.5-inch wedges and the onion into 1-inch thick petals, keeping them separate for now. Slice the lemon into 1/4-inch rounds and mince the garlic cloves finely (I find freshly minced garlic gives you a much more robust, aromatic flavor than pre-minced). Have all your ingredients prepped and within reach before you begin assembling the dish.
In a small bowl, whisk together the olive oil, lemon juice, minced garlic, rosemary, oregano, red pepper flakes, and nutmeg. This aromatic mixture will be drizzled over the dish to infuse all the components with Mediterranean flavors. Set aside until ready to use.
Spread the potato wedges and onion petals in a single layer in a large roasting pan (approximately 9x13 inches or similar). Season them generously with salt and pepper, tossing to coat evenly. These vegetables will cook alongside the chicken and become tender and golden by the time everything is done.
Nestle the seasoned chicken thighs skin-side up among the vegetables in the roasting pan. Distribute the lemon slices over and around the chicken. Pour the chicken broth around (not over) the chicken to keep the skin from getting soggy. Then pour the herb and oil mixture from Step 2 evenly over everything, ensuring the chicken skin gets a good coating. Transfer to the preheated 375°F oven and roast for 45-60 minutes, until the chicken reaches an internal temperature of 165°F at the thickest part of the thigh.
Once the chicken reaches 165°F, check the skin color. If you'd like deeper browning and crisper skin—which I recommend for better texture—increase the oven temperature to 425°F and roast for 15-20 minutes more, or use the broiler for 3-5 minutes, watching carefully to prevent burning. Remove from heat and scatter the kalamata olives over the dish, nestling them among the chicken and vegetables. Finish with a generous handful of fresh chopped parsley for brightness and color.
Transfer the chicken and roasted vegetables to a serving platter or serve directly from the pan for a rustic presentation. Serve alongside Greek salad, tzatziki sauce, and warm pita bread to complete the Mediterranean experience. The pan juices can be drizzled over individual portions for extra flavor.