Activate Yeast: Combine warm water with sugar, then sprinkle the active dry yeast over the top. Let it foam for about 10-15 minutes until bubbly.

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

First Rise: Cover the bowl tightly with plastic wrap and refrigerate the dough for at least 12 hours.

Second Rise: Grease a baking pan with melted unsalted butter. Gently deflate the dough and place it in the pan, allow it to rise for 1.5-2 hours.

Prepare Brown Butter: Melt the unsalted butter over medium heat until it turns golden brown and smells nutty. Remove from heat and let it cool slightly.

Make Cinnamon Topping: In a bowl, mix the warm brown butter with light brown sugar and cinnamon until the sugar dissolves.

Dimple Dough: Preheat your oven to 450°F. Gently press deep dimples into the risen dough using your fingers, then drizzle the cinnamon-butter mixture evenly over the top.

Bake: Place the pan in the oven and bake for 20-25 minutes, until golden brown on top.

Finish with Icing: In a medium bowl, combine powdered sugar, milk, and vanilla extract. Mix until smooth, then drizzle over the warm focaccia.