Add water to a large bowl. Next, add flour, then the yeast on one side of the flour, and salt on the other, making sure the two don't touch each other before you start mixing. Mix by hand, squeezing the dough between your fingers until a sticky homogeneous mass is formed. Cover the bowl with plastic wrap and let rest for 20 minutes.
After 20 minutes, perform a set of stretches and folds, then another one after 20 minutes, and another one 20 minutes later. Shape the dough into a ball and rub it with two tablespoons of olive oil. Cover the bowl with plastic wrap and let the dough rest for another 20 minutes.
Transfer the dough to a 13" by 9" aluminum cake pan greased with two tablespoons of butter. Stretch it to fill the entire bottom of the pan. Cover with plastic and refrigerate overnight and for up to 24 hours.
Remove the dough from the fridge two hours before baking and let proof at room temperature, covered.
Preheat the oven with a baking stone positioned on the top shelf to 500F.
Liberally drizzle olive oil over the top of the dough. Using your fingers, make deep dimples all over the surface of the dough. Spread the toppings and finish with a light drizzle of olive oil.
Bake at 500F with convection for 12 minutes. Every oven bakes differently so start checking early, your bread may be done sooner, or you may need to add a few minutes to the baking time.
Carefully transfer the focaccia to a large cutting board, slice, and serve while hot. This is when it tastes best.