Preheat oven to 375˚F.
Using paper towels, pat dry the whole chicken, inside and out.
Using the handle of a wooden spoon, carefully insert it underneath the skin, beginning at the neck. Slowly separate the skin from the meat without tearing through the skin. Set the chicken aside.
In a small mixing bowl, combine softened cream cheese, rosemary, chopped garlic, and pepper; mix until creamy and combined.
Using your fingers or a spoon, spread the cream cheese mixture under the skin, around the entire bird, out to the thighs and legs. I find it easier to spoon a large chunk of the cream cheese under the skin; then I use my fingers to spread it around by rubbing the chicken on top.
Place slices of lemon inside the cavity and set aside.
Butter a large baking dish with one tablespoon butter.
Place potatoes, carrots, onions, and garlic in the baking dish; toss with salt, pepper, and olive oil.
Place the whole chicken on top of the veggies, breast-side up.
Sprinkle salt over the chicken and drizzle with a little bit of olive oil.
Place in oven and roast for 1 hour.
Remove from oven and carefully flip the entire bird.
Bake for 20 to 30 minutes more, or until lightly browned and cooked through. Chicken is cooked through when its internal temperature registers at 165˚F.
Remove from oven and transfer to a cutting board or plate; let stand 10 to 15 minutes.
Transfer veggies and chicken to a large serving dish; spoon juices over the chicken and serve.