Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Rinse and drain the chickpeas, then pat them extremely dry with a clean kitchen towel to ensure they get crispy.
Cut the chicken breast into 1-inch bite-sized pieces and pat dry with paper towels.
In a large mixing bowl, whisk together the olive oil, lemon juice, lemon zest, dried oregano, garlic powder, sea salt, and black pepper.
Add the chicken and chickpeas to the bowl and toss thoroughly until every piece is evenly coated in the herb mixture.
Spread the mixture in a single layer on the prepared baking sheet, making sure not to overcrowd the pan.
Roast for 20 to 22 minutes, tossing halfway through, until the chicken is cooked through and the chickpeas are golden and crisp.
Place the fresh baby spinach in a serving bowl and top with the hot roasted chicken and chickpea mixture to lightly wilt the greens.