Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Drain and rinse the chickpeas, then spread them onto a clean kitchen towel and pat them until they are completely dry.
Cut the chicken breast into uniform 1-inch cubes to ensure even cooking.
In a medium mixing bowl, whisk together the olive oil, lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper.
Add the dried chickpeas and chicken cubes to the bowl, tossing thoroughly until every piece is coated in the marinade.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the chickpeas and chicken are not overcrowded.
Roast for 20 to 25 minutes, giving the pan a good shake halfway through, until the chicken is cooked through and the chickpeas are slightly golden and crisp.
Place the fresh baby spinach in a serving bowl and top immediately with the hot chicken and chickpea mixture to gently wilt the greens before serving.