Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Drain and rinse the chickpeas, then pat them thoroughly dry with a clean kitchen towel to ensure they get maximum crunch.
Dice the chicken breast into uniform 1-inch pieces and chop the red bell pepper into similar sized chunks.
In a small bowl, whisk together the olive oil, lemon juice, lemon zest, minced garlic, dried oregano, sea salt, and black pepper.
Place the chicken, chickpeas, and bell peppers on the prepared baking sheet and drizzle with the lemon-herb dressing, tossing until every piece is well coated.
Spread the mixture into a single layer and roast for 20-25 minutes, tossing halfway through, until the chicken is cooked through and the chickpeas are golden brown.
Place the fresh spinach in a serving bowl and top with the hot roasted chicken and chickpea mixture, allowing the heat to slightly wilt the greens before serving.