In a medium-sized, clean bowl, add the water, yeast, granulated sugar, and honey. Allow to dissolve. In a clean, large bowl, add flour and salt. Whisk to combine. Pour in the yeast mixture and olive oil. Stir together with a rubber spatula until just incorporated, and a shaggy dough forms.
Scrape the sides of the bowl clean and cover tightly with plastic wrap. Let sit for 12 hours or over night until doubled in volume.
Pour 2 to 3 tablespoons olive oil on a small rimmed baking sheet. When the dough has fermented for at least 12 hours, gently use a rubber spatula and your hands to peel it away from the sides of the bowl and place it on the oiled baking sheet.
Add about 1 more tablespoon of olive oil over the dough and spread it across the top of the dough. Gently pull the dough, stretching it to the edge of the pan. The dough will recoil a bit, and so you should stretch it as far as you can, let it set for 15 minutes, and then come back to stretch it again until the dough fits across the entire pan.
Once the dough is stretched across the pan, dimple the dough with deep dents with your fingers. Let the dough rise for 45 minutes until the dough is light and bubbly.
When ready to bake, preheat your oven to 450°F. Sprinkle the focaccia with rosemary (if desired) and flaky salt. Bake for 25 minutes or until top is golden and bottom is crisp and golden. Remove from oven.
Drizzle with 1-2 more tablespoons of olive oil and allow to cool until warm and no longer hot. Serve with a side of olive oil for dipping! Enjoy.