Make the overnight focaccia dough per my instructions up to (and including) step 9.
Preheat the oven to 550 degrees F (or however high your oven goes). If you have a pizza stone, place it on the bottom rack.
Once the 45 minute proof is up, add the topping to the focaccia by spreading the tomato sauce on top, then adding the oregano, red pepper flakes, salt, and olive oil. (Note: If you want a saucier focaccia, let the focaccia bake for 15 minutes, and then add the topping and continue baking for another 15 minutes.)
Lower the oven to 425 degrees F and bake for 30 minutes on the center rack. In the last 15 minutes move the tray to bake on the bottom rack, on top of the pizza stone if you added one.
Let the focaccia rest for 7 minutes in the tray, and then transfer to a wire rack to cool a bit before cutting.