Heat oven to 375°F. Line a baking sheet with aluminum foil and spread sliced potatoes and sliced onions evenly on the baking sheet. Place a cooling rack on the baking sheet, over top of the potatoes and onions.
Stir together the chopped olives, 1 teaspoon lemon zest, and the minced garlic in a small bowl. Set aside. In a separate small bowl, mix together 1 1/2 Tablespoons smoked paprika, 1 1/2 teaspoons olive oil, 3/4 teaspoon kosher salt, and 1/8 teaspoon freshly ground black pepper to form a paste. Set aside.
Using sharp kitchen shears, trim excess skin and fat from the chicken thighs. Cut a slit along the bone of the chicken thigh, and carefully cut the bone from the thigh, being careful not to cut any holes in the chicken. (If you don't have kitchen shears, carefully use a paring knife to cut away excess skin, fat, and bones from the chicken).
Carefully stuff about 2 Tablespoons of the olive mixture under the skin of each chicken thigh. Rub the skin and meat of each thigh evenly with the paprika mixture.
Place chicken thighs skin side up on the cooling rack over the potatoes and onions. Bake until the skin is crispy, about 60 minutes. Divide potatoes and onions evenly among 4 plates, and top each with one chicken thigh.
Notes
Removing the chicken bones is optional, but makes it much easier to eat the thighs. If you decide not to remove the bones, you may need to add 5 minutes on to the cooking time.