In a small bowl, whisk together lemon juice, shallot, and 3 tablespoons oil; season with salt and pepper and set aside.
In a large skillet, heat 1 tablespoon oil over medium-high. Season lamb chops with salt and pepper and cook until medium-rare, 10 minutes, flipping once. Transfer to a work surface and loosely tent with foil. Let rest 5 minutes, then cut away from bone and thinly slice.
In a large bowl, toss together spinach and pears. Divide among four plates, top with lamb, and drizzle with dressing.