The process for making focaccia starts the same as for bread. Follow that process up through the bulk fermentation. I'll usually make focaccia and a loaf of bread at the same time.
Since it's flat, focaccia doesn't need nearly as much strength as bread. If you're making a loaf and it's clearly not gonna stand up during the proof, you can always pivot to focaccia.
If I'm doing only focaccia, I'll typically go a bit wetter and a bit less whole grain than my standard loaf of bread. Here's an example at 10% whole wheat and 80% hydration.
Split off the portion of the dough to be used for focaccia. The goal here is to preserve much of the gas trapped in the dough. It doesn't need much strength at all, so handle as little as possible, just a little light shaping into a loose ball.
Pour a generous amount of olive oil in a sheet pan. Carefully place the dough into the middle of the pan Lightly oil the top of the dough to prevent it from drying out. Gently stretch the dough out, but don't force it or deflate it, it'll stretch more as it proofs.
You can optionally put the focaccia in the fridge to delay the bake. To do so, oil a wide mixing bowl, place the dough inside it, oil the top of the dough. Cover with plastic wrap and put in the fridge for up to a day.
Preheat the oven to 450°
The dough shouldn't need long to rise - start preheating shortly after shaping
Sardenaira is a close relative to focaccia from Liguria. I make it as a focaccia with a particular set of toppings. It's salty and fantastic.
Sauce - Make a basic tomato sauce, but with anchovies dissolved into it. Spread this over the dough.
Toppings - Dot the top of the sardenaira with: