Pre-heat oven to 425 degrees Fahrenheit and lightly drizzle olive oil to the bottom of a cast iron pan.
Pat the chicken dry very well (this will help the seasoning and butter stick well), and place chicken breast side down.
Use a pair of kitchen shears and cut along each side of the back bone/spine.
Remove the back bone (you can save and freeze later for stock).
Turn chicken over, so breast side is up and use the heal of your hands to press firmly on the breast bone, flattening the chicken until you hear it crack.
Once the chicken is butterflied, massage the compound butter all over the chicken, both over and under and under the skin as best as you can.
Place chicken, breast side up in the oiled cast iron and nestle in cut lemons.
Roast chicken for about 30 minutes until deep golden brown and cooked to 165 degrees Fahrenheit, internally.
Let chicken rest for at least 15 minutes before cutting into it.