Make the Dough
In a large bowl, whisk together the flour, kosher salt, and instant yeast. Add the water. Mix with a rubber spatula until the liquid is absorbed and a sticky, shaggy dough forms. Cover and rest for 30 minutes.

Stretch and Fold
Wet your hands. Grab an edge of the dough, pull it up, and fold it toward the center. Repeat this 8–10 times around the bowl until the dough feels smoother and cohesive.

Cold Ferment
Lightly rub the dough surface with olive oil. Cover tightly and refrigerate for at least 12 hours (up to 3 days).

Prepare Pan
Grease a 9×13-inch baking pan with softened butter (crucial for release!). Pour 2 tablespoons olive oil into the pan.

First Rise
Gently deflate the cold dough and transfer it to the prepared pan. Turn it to coat in the oil. Cover and let rest at room temperature for 1.5 hours.

Make Filling 1
In a small skillet, melt 4 tablespoons (half) of the butter. Whisk in 4 tablespoons of brown sugar, 2 teaspoons of cinnamon, and a pinch of flaky salt.

Fill & Fold
Gently stretch the dough to fill the pan. Pour the filling over the dough. Fold the dough “envelope style” (fold one short end over two-thirds, then the other end over that). Rotate the dough so the open ends face the short sides of the pan. Cover and rest for another 1.5 hours.

Second Rise & Prep
Preheat oven to 425°F (220°C).

Make Filling 2
Melt the remaining 4 tablespoons butter. Whisk in the remaining 4 tablespoons brown sugar and 2 teaspoons cinnamon.

Dimple & Top
Pour the second batch of filling over the dough. Using lightly oiled fingers, press straight down to create deep dimples all over the dough (like traditional focaccia). Sprinkle with flaky sea salt.

Bake
Bake for 25 minutes until deep golden brown.

Cool & Glaze
Remove from oven. Let cool in the pan for 2–3 minutes, then transfer to a rack (run a spatula around the edges first to loosen caramelized sugar). Whisk the glaze ingredients together and drizzle over the warm bread.