Preheat the oven to 400℉

Prepare the chicken by placing the chicken breast side down and use a pair of kitchen shears to cut along each side of the backbone to remove. The kitchen shears cut through the bones very easily.
Flip the chicken over and give a gently press to finish flattening it out.

Use paper towels to completely dry the skin of the chicken.
Combine softened butter and lemon pepper seasoning together.
Place a small amount of the butter mixture underneath the skin on the breast area. Use your fingers to gently slide the seasoned butter back under the skin and over the breast meat. Apply the rest of the seasoned butter mixture to all of the skin areas of the chicken.

Add a tablespoon of vegetable oil to coat the bottom of a large cast iron skillet. If you don't have a skillet large enough to accommodate the flattened bird, feel free to use a roasting pan.

Place the chicken into the skillet. Bake for 45 minutes.

After 45 minutes remove the chicken from the oven and allow to rest 15 minutes before carving. Garnish with lemon slices and fresh thyme if desired.