Preheat your oven to 425 degrees Fahrenheit. Place parchment paper on a rimmed baking sheet, and set aside.
Place the chicken breast side down on a cutting board. Locate the backbone. It is easiest to find by looking for the small piece of tailbone that sticks out of the bottom of the bird. Use very sharp kitchen shears to cut on one side of the backbone all the way to the top of the chicken. Then repeat on the other side to full remove the backbone. (See photos in the post.)
Turn the chicken over, spreading the chicken out flat. Press down so it lays fully flat. You may hear a pop - this is the breastbone breaking. Place the chicken on the prepared baking sheet.
In a small bowl combine the butter, Italian seasoning, kosher salt, and black pepper. Gently spread the mixture under the skin of the chicken, working to cover the breasts and thighs evenly.
3 tablespoons unsalted butter, 1 tablespoon Italian seasoning, 1 teaspoon kosher salt, 1/4 teaspoon black pepper
Spread 1 tablespoon olive oil over the chicken skin, coating it evenly. Season with kosher salt and freshly ground black pepper.
In a medium bowl, toss the vegetables with olive oil, Italian seasoning, kosher salt, and black pepper. Spread the vegetables around the chicken on the prepared baking sheet.
3 carrots, 1 pound Yukon gold baby potatoes, 2 tablespoons olive oil, 1/2 tablespoon Italian seasoning, 1 teaspoon kosher salt, 1/4 teaspoon black pepper
Bake for 45 to 55 minutes or until the chicken reads 165 degrees Fahrenheit with an instant read thermometer. Watch closely at the end of the cooking time and cover the chicken with foil if the skin begins to brown too much.
Carve the chicken and serve with the vegetables.