Pre-heat the oven to 400º Fahrenheit.
Gently rinse the branzino to remove any excess scales and/or any blood. Pat dry.
Using 1-2 lemons, thinly slice until you have at least 8 slices, though more is fine.
Line your sheet pan with parchment paper.
Generously season the inside and outside of the fish with salt and pepper
Drizzle about half of the olive oil on the paper, then place the fish on top.
Add remaining olive oil (or more) to the top and inside of the fish.
Stuff the cavity of the branzino with 2 rosemary sprigs and at least 4 lemon slices per fish.
Add the drained olives onto the sheet pan around the fish.
Roast for 10-12 minutes.
After 10-12 minutes of roasting, turn the broiler onto the highest setting and roast again for 2-3 minutes on each side to crisp the skin.
Remove and allow to cool slightly.
Serve warm and garnish with chopped parsley and lemon wedges.
Be aware of bones while eating.