Preheat the oven to 375°F.

Place the chicken breasts flat on a cutting board and, holding a knife parallel to the cutting board, begin cutting into the side of the chicken breast at one end, creating a long cut lengthwise. Continue cutting into the chicken, creating a "pocket" that leaves about 1/4-inch (at both ends and along the opposite side) intact.

Microwave spinach until thawed. Transfer thawed spinach to a fine mesh strainer and, squeezing spinach with hands, thoroughly wring dry.

Add the spinach to a mixing bowl, along with the Parmesan, diced artichokes, cream cheese, and garlic powder. Season with salt and pepper and stir until well combined.

Stuff the spinach-artichoke mixture into the "pocket" of each piece of chicken. Heat the olive oil in a sauté pan over medium-high heat. When oil is hot, place the stuffed chicken in the pan and allow it to cook, without moving it or flipping it, for about 3-5 minutes. When the bottom edges begin to turn golden, use a spatula to flip the chicken and cook the second side for about 2-4 minutes more.

Use a spatula to transfer the chicken to a casserole dish or baking sheet and cook in the oven for about 9-12 minutes, or until chicken is cooked through to the center.

Serve.