This dish couldn't be easier, but the payoff is succulent, sweet, savory and so much more than the sum of its parts.
Preheat oven to 375°. Season chicken on both sides with salt and pepper. In an extra-large oven-safe skillet, melt butter over medium-high. Add chicken thighs; cook until nicely browned, about 4 minutes per side. (If you don't have a pan large enough to fit all the thighs, brown them in batches and transfer to a 3-quart baking dish to finish in the oven.)
Add olives, olive brine, lemon juice, dates, garlic and thyme to pan. Transfer pan to oven and roast until chicken is done (175°), about 35 minutes.