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

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

Cover the bowl and refrigerate for at least 12 hours to allow for the first rise.

Remove dough from the refrigerator, grease a 9x13-inch pan with melted unsalted butter, and transfer the dough, spreading it evenly.

In a saucepan, melt unsalted butter until golden brown and nutty.

Mix cooled brown butter with light brown sugar and cinnamon until combined; set aside.

Preheat oven to 450°F. Make dimples in the risen dough and drizzle with brown butter topping.

Bake for 20 to 25 minutes until golden brown. Allow to cool for 10 minutes.

Whisk together powdered sugar, milk, and vanilla extract for the icing. Drizzle over the warm focaccia.

Slice and serve.