Preheat your toaster oven to 425°F (220°C) on the bake setting and position the rack in the center. Line your toaster oven baking pan with aluminum foil and set a wire rack on top if you have one that fits.

Pat the chicken thighs completely dry with paper towels — this is the key to crispy skin. In a small bowl, combine the za'atar, garlic powder, 1/2 teaspoon salt, and black pepper.

Drizzle 1 tablespoon of olive oil over the chicken thighs and rub it in well on all sides. Sprinkle the za'atar spice mixture evenly over the chicken, pressing it gently into the skin to adhere.

In a medium bowl, toss the drained chickpeas with the remaining 1 tablespoon olive oil, sliced garlic, cumin, smoked paprika, lemon zest, and the remaining 1/4 teaspoon salt. Stir to combine evenly.

Spread the chickpea mixture in an even layer around the edges of the foil-lined pan, leaving the center open for the chicken. Nestle the seasoned chicken thighs skin-side up in the center of the pan.

Slide the pan into the preheated toaster oven and roast for 28 to 32 minutes, until the chicken skin is deep golden brown and crispy and an instant-read thermometer inserted into the thickest part reads 165°F (74°C).

Carefully remove the pan from the toaster oven. Scatter the baby spinach around the chicken directly onto the hot chickpeas and return the pan to the oven for 2 minutes, just until the spinach wilts.

Remove the pan and drizzle the lemon juice over the chickpeas and spinach. Stir the chickpea and spinach mixture gently to combine. Let the chicken rest for 5 minutes before serving.

Plate the chicken thighs over a generous scoop of the lemony chickpeas and spinach. Scatter fresh parsley on top and serve with lemon wedges and a dollop of Greek yogurt if desired.