Place one chicken breast on a cutting board. Using a sharp knife, slice each chicken breast horizontally partway through so you can open it like a book (butterfly). Place each opened breast between two pieces of plastic wrap and pound to an even thickness. Pat the chicken dry with paper towels.
In a small bowl, combine 2 tablespoons Italian seasoning, 2 teaspoons garlic powder, 1 teaspoon salt, 1/2 teaspoon MSG (optional), 1/4 teaspoon ground black pepper, and 1/2 teaspoon paprika.
Sprinkle the seasoning mix evenly over both sides of the chicken breasts, pressing gently so the seasoning adheres.
Let the seasoned chicken rest for 30 minutes at room temperature, or transfer to a covered container and refrigerate for up to overnight.
When ready to cook, heat 1 tablespoon canola oil in a large cast-iron skillet over medium-high heat until hot.
Add the chicken breasts to the skillet and cook about 5 minutes on the first side without moving them, then flip and cook about 5 minutes on the second side, until the exterior is browned and the internal temperature reaches 165°F.
Transfer the cooked chicken to a plate and pour 2 tablespoons melted butter over the top.
While the chicken is resting, place the lemon halves cut-side down in the hot skillet and cook about 3 minutes, until the cut surfaces are charred.
Squeeze the charred lemon over the chicken, garnish with fresh parsley, and serve.