In a large mixing bowl, combine the flour, instant yeast, and salt. Stir until blended.

Gradually add lukewarm water to the dry mixture, stirring until a sticky dough forms. Cover and let rest for 30 minutes.

Refrigerate the dough for 12 hours to 3 days to enhance flavor.

Preheat your oven to 425°F (220°C) and coat a 9x13-inch baking pan with olive oil.

Turn the chilled dough onto the prepared baking pan and stretch to fill the pan. Cover and let rise for 1.5 hours.

Melt the butter, then mix with brown sugar and cinnamon in a small bowl.

Create dimples in the risen dough and pour the cinnamon-sugar mixture over the top. Add flaky sea salt.

Bake for 20-25 minutes until golden brown.

Let cool for 10 minutes, then drizzle with a glaze made from powdered sugar and milk.

Cut into squares and serve warm.