Seven simple ingredients are the building blocks for this pan-roasted meal.
Preheat oven to 450 degrees. In a medium saucepan, bring potatoes to a boil in salted water and cook until tender when pierced with a knife, 15 minutes.
Meanwhile, season chicken with salt, pepper, and thyme. In a large ovenproof skillet, heat 1 teaspoon olive oil over medium-high. Cook chicken, skin side down, until golden and crisp, 5 minutes. Flip, then add shallots; cook until chicken is browned, 5 minutes. Flip shallots, then transfer skillet to oven. Roast until chicken is cooked through, 15 minutes.
Reserve 3/4 cup cooking water from potatoes. Drain potatoes and return to pan. Add 2 teaspoons oil, lemon zest, and reserved cooking water; season with salt and pepper and roughly mash.
Transfer chicken and shallots to a platter and heat skillet over medium. Add remaining 1 teaspoon oil and garlic and stir until fragrant, 30 seconds. Gradually add spinach, and toss until wilted, 3 to 5 minutes. Season to taste with salt, pepper, and lemon juice. Serve chicken with shallots, potatoes, and spinach.