In a mixing bowl, combine warm water with granulated sugar, then sprinkle active dry yeast on top. Allow to sit for 10-15 minutes until foamy.

In a large bowl, whisk together bread flour and salt. Once yeast is foamy, add it to the flour with olive oil and stir until sticky.

Cover the bowl tightly and place it in the refrigerator. Let the dough rest for at least 12 hours or overnight.

Grease a baking pan with melted butter and pour any remaining melted butter into the bottom. After deflating the dough, transfer it to the pan.

In a saucepan, melt unsalted butter until it turns amber, then mix in light brown sugar and cinnamon, stirring until dissolved.

Preheat oven to 450°F. Press dimples in the dough and drizzle the cinnamon-butter mixture over it.

Bake the focaccia for 20-25 minutes until golden brown. Remove from oven and let it cool for about 10 minutes.

Mix powdered sugar, milk, and vanilla extract until smooth, drizzle over the cooled focaccia, slice, and serve warm.