Prepare the Dough (Night Before)

1. In a large mixing bowl, stir together the 100 g active sourdough starter, 375 g filtered water, and 30 g honey until the starter is mostly dissolved and the mix looks milky.

2. Add the 500 g bread flour and 10 g salt. Mix until there are no dry bits left—use a spatula or your hand to bring it together.

3. Perform 2–3 sets of stretch and folds (every 20–30 minutes) during the first hour to build structure.

4. Cover the bowl (with plastic wrap or a lid) and leave the dough to bulk ferment overnight (8–12 hours) at room temperature. Don’t worry if it overferments slightly—the recipe handles it gracefully.

2. Baking Morning

1. Preheat your oven to 425 °F (≈ 218 °C).

2. Peel and slice the apple, and set aside.

3. In a small bowl, melt the 113 g unsalted butter. Use a portion to grease a 9×13″ baking pan or a 12″ cast-iron skillet.

4. In another bowl, mix the remaining melted butter with 1–2 tbsp cinnamon and 60 g brown sugar. Set this aside.

5. Transfer your fermented dough into the greased pan. Gently stretch it to fill the bottom, but don’t overwork it.

6. Drizzle the cinnamon-sugar butter mixture evenly across the surface of the dough.

7. Distribute the apple slices on top.

8. Use your fingers to dimple the dough, pressing toppings gently into the surface.

3. Bake

1. Cover the pan with foil and bake at 425 °F for 15 minutes.

2. After 15 minutes, remove the foil and continue to bake uncovered for another 20 minutes, or until the top is golden brown and the interior reaches 205 °F (≈ 96 °C).

3. Let it rest a few minutes after baking.

4. Glaze & Serve

While the focaccia bakes (or rests), whisk together 120 g powdered sugar, 1 tsp vanilla extract, 1 tbsp milk, and a pinch of salt until you have a smooth icing.
Drizzle the glaze over the warm focaccia, slice, and enjoy!