Activate Yeast: Combine warm water and granulated sugar in a bowl. Sprinkle active dry yeast over the top and let sit for 10-15 minutes until frothy.

Mix Dough: In a large bowl, whisk together bread flour and salt. Pour in yeast mixture and olive oil; stir until sticky dough forms.

First Rise: Place dough in greased bowl, cover, and refrigerate for at least 12 hours.

Second Rise: Preheat oven to 450°F. Deflate the dough, transfer to greased pan, and let rise for 1.5 to 2 hours.

Prepare Topping: Melt butter in a saucepan until golden, then mix in light brown sugar and cinnamon.

Dimple Dough: Create dimples in the risen dough and drizzle the brown butter mixture over the top.

Bake: Bake for 20-25 minutes until golden brown. Let cool in the pan for about 10 minutes.

Finish with Icing: Whisk together powdered sugar, milk, and vanilla extract until smooth and drizzle over the warm focaccia.