Adjust the oven rack to the center and preheat the broiler to high. Line a large sheet pan with foil and spray generously with cooking spray.
Trim the fat from the chicken and cut it into 1-½-inch pieces. Pat dry with paper towels.
In a large bowl, whisk together olive oil, chicken broth, 1 tsp lemon zest, 2 tbsp lemon juice, 2 tsp minced garlic, red pepper flakes, and Italian seasoning. Season with salt and pepper to taste.
Add the chicken pieces to the marinade and toss to coat. Cover and let chill in the refrigerator for 30 minutes to 1 hour.
In a second large bowl, stir together panko breadcrumbs, grated Parmesan, garlic powder, and ½ teaspoon each of salt and pepper.
Use tongs to remove the chicken from the marinade, allowing excess to drip off. Toss in the breadcrumb mixture until evenly coated.
Thread the chicken onto skewers and place them spaced apart on the prepared pan. Press any leftover crumbs onto the chicken. Spray with cooking spray.
Broil for 10-12 minutes, watching closely until the chicken reaches 160°F and the coating is golden.
While it cooks, melt unsalted butter with remaining minced garlic in a microwave-safe dish. Stir in 1 tbsp lemon juice and parsley.
Drizzle the garlic butter over the cooked Chicken Spiedini and serve immediately with lemon wedges.
