Combine all ingredients EXCEPT olive oil in a large bowl. Mix until a shaggy dough, and flour is fully absorbed.
Cover and set aside in a warm environment for 30 minutes.
After 30 minutes, imagine the bowl divided into four corners. Scoop one corner from the bottom, lift as high as you can without breaking the dough, then fold over into the center. Rotate the bowl to repeat with the remaining 3 "corners." This helps to trap air in the dough.
Cover and rest in a warm environment for 30 minutes. (TIP: If the dough is still sticky at this point, add up to 80 grams more flour to help it become workable. Winter months and elevation can also play into bread baking.)
After 30 minutes, add the chopped chives and half of the grated cheeses. Repeat the lift and fold process explained above.
Cover and rest 30 minutes.
Line a 9x13" baking pan with parchment paper. Drizzle generously with olive oil.
Repeat the lift and fold process once more, then transfer the dough out to a lightly floured surface. Gently stretching the dough from underneath, stretch out to fit the size of a 9x13" baking pan.
If wanting to make it pull-apart dinner roll-style: Use a dough scraper or knife to slice the stretched focaccia into individual rolls.
Place in the prepared baking pan.
Cover and let rest 30 minutes.
Preheat the oven to 425F.
Drizzle the focaccia generously with olive oil. Top the focaccia with the remaining grated cheeses, then grease your hands with olive oil to create dimples in the dough with your fingers. Season with flaky salt.
Bake for 20-25 minutes, rotating the pan halfway through, until deeply golden on top.