Preheat oven to 400°F. Line a baking sheet with aluminum foil and spray the foil with nonstick cooking spray.
In a medium bowl, whisk together 1/2 cup honey and 2 teaspoons warm water until smooth. Remove and set aside one-quarter of this honey mixture in a small bowl for drizzling later.
In a separate bowl, combine 1/2 cup whole-wheat panko breadcrumbs, 1 teaspoon Italian seasoning, 1/4 teaspoon cayenne pepper, 1/4 teaspoon paprika, 1/2 teaspoon garlic powder, 1/4 teaspoon red pepper flakes, 1/4 teaspoon kosher salt, and 1/4 teaspoon chili powder. Stir to evenly mix the crumbs and spices.
Add the 1‑inch chicken breast cubes to the larger honey-water bowl and toss until each piece is coated on all sides.
Working in batches if needed, transfer coated chicken pieces to the panko-spice mixture and press gently so the crumbs adhere, turning to coat evenly. Shake off excess crumbs and arrange the coated pieces in a single layer on the prepared baking sheet, leaving space between pieces.
Bake in the preheated oven for 10 to 12 minutes. Use tongs to turn each piece, then return the pan to the oven and bake until the chicken is golden, crispy, and cooked through—about 10 minutes more (or until internal temperature reaches 165°F if using a thermometer).
Remove the baking sheet from the oven, drizzle the reserved honey-water mixture over the hot chicken, and sprinkle the diced green onions on top. Serve immediately.