Spread two tablespoons of oil long the baking sheet. Don't put too much oil or it will splatter all over your oven unless you line your pan with potatoes or vegetables.
Place the springs of rosemary and garlic slices in the middle so that they will be completely covered by the chicken when you place it on the pan.
Using a sharp knife or kitchen shears, cut the backbone out of the chicken, cutting down both sides of the backbone and removing it. (Save the backbone in a bag in the freezer to make broth in the future.)
Place the chicken, back side down, opened wide, on the baking sheet over the rosemary and garlic.
Press on the breast to flatten the chicken.
Drizzle the chicken with the a little olive oil.
Sprinkle salt, pepper and Herbes de Provence over the chicken.
Spread the sliced lemon around the chicken and on the pan.
Bake the chicken at 450°F for 40-50 minutes until nice and brown and the internal temperature reaches 185F degrees (breast) and when you poke it, the juices run clear.
Remove the chicken from the oven and let it rest for 10 minutes before carving and serving.
Notes
I looked at a few videos on YouTube to see what temperature to roast the chicken and found it varies. Valerie Bertinelli (the actress) had the simplest method, and I modeled my recipe after hers. The extra time in the recipe is for letting the chicken rest (10 minutes).IMPORTANT NOTE 2: If you put small, new potatoes sliced in half all around the pan surrounding the chicken, it won't splatter as much in your oven. I didn't do this the first two times I made this recipe, and I had to clean my oven both times!