Mix the dough. In a large bowl, whisk warm water, sugar, and yeast. Add flour, salt, and olive oil. Stir with a spatula until no dry spots remain. The dough will be sticky—perfect.

First rise. Cover the bowl and let it rise at room temperature until doubled, about 60–90 minutes. For more flavor, refrigerate up to 24 hours after a 30-minute rest, then bring to room temp before shaping.

Prepare the pan. Generously oil a 9x13-inch pan or a large cast-iron skillet. Pour in 2–3 tablespoons olive oil so the bottom is slick.

Transfer and stretch. Scrape the dough into the pan. With oiled fingers, gently stretch it toward the edges. If it springs back, rest 10 minutes and try again.

Make the cinnamon mixture. Stir melted butter, brown sugar, cinnamon, salt, and vanilla until smooth and syrupy.

Dimple and swirl. With oiled fingers, press deep dimples all over the dough. Drizzle the cinnamon mixture in ribbons and little pools, encouraging it into the dimples for that signature swirl.

Second rise. Let the dough rise uncovered for 20–30 minutes, until slightly puffy. Meanwhile, preheat the oven to 425°F (220°C).

Bake. Bake 18–24 minutes, until the top is deeply golden and the cinnamon sugar is bubbling at the edges. The bottom should be crisp but not dark.

Optional glaze. Whisk powdered sugar, milk, vanilla, and a pinch of salt until smooth. Drizzle over the warm focaccia.

Finish and serve. For bakery shine, brush the crust with a little olive oil right after baking. Cool 10 minutes, then cut or tear into squares. Serve warm.