While tomato sauce simmers, remove the cabbage leaves from the head. Remove the leaves and place on a cooling rack or paper towels. Once cool enough to handle, use a knife to gently shave down the thick central vein running down the middle of each leaf. Be careful not to cut through the leaf.
Scoop 2 tablespoons of filling into the center of each cabbage leaf, towards the base end. Roll up the leaf by folding each side over the filling before rolling away from the base. Place the rolled cabbage leaf in the baking tray. Repeat for the remaining leaves.
When all leaves are rolled and arranged on baking tray, pour the tomato sauce over them
Transfer tray to preheated oven and bake for 50 minutes
When ready, remove the tray from the oven and allow to cool for 10 minutes before serving