Pat the chicken dry and cut into bite-size pieces.
Place the chicken in a mixing bowl, drizzle with 1 tablespoon olive oil, and toss with the garlic and herb seasoning until evenly coated.
Heat 1 tablespoon olive oil in a 12-inch cast iron skillet over medium-high heat until shimmering.
Add the chicken pieces in a single layer and cook about 3 minutes per side until golden brown and cooked through.
Reduce heat to medium, add the butter and minced garlic to the pan, and cook until the butter melts and the garlic is fragrant, about 1–2 minutes.
Toss the chicken in the garlic butter to coat, then season with salt and black pepper to taste.
Serve immediately, garnished with fresh parsley, grated Parmesan, and red pepper flakes if desired.