In a small bowl, combine warm water with granulated sugar. Sprinkle the active dry yeast over the top and let it sit for 10-15 minutes until foamy.

In a large bowl, whisk together bread flour and salt. Add the foamy yeast mixture and olive oil. Stir until a sticky dough forms.

Place the dough in a greased bowl, cover it, and refrigerate for at least 12 hours.

Remove the dough from the fridge and let it sit at room temperature for 30 minutes. Grease a baking pan, then transfer and stretch the dough evenly in the pan and cover it to rise.

Melt unsalted butter in a saucepan over medium heat until golden brown and nutty. Let cool slightly.

Combine light brown sugar and cinnamon into the browned butter until dissolved.

Preheat oven to 450°F. Press dimples into the dough and drizzle the brown butter mixture over it.

Bake the focaccia for 20-25 minutes until golden brown. Let cool for 10 minutes.

For the icing, whisk powdered sugar, milk, and vanilla extract together, then drizzle over the warm focaccia.