Combine flour and salt in a large bowl. Make a well in the center and add warm water and 3 tablespoons of olive oil. Mix until a shaggy dough forms.

Knead the dough on a floured surface for 8-10 minutes until smooth and elastic. Wrap in plastic wrap and rest at room temperature for 30 minutes.

Preheat oven to 250°C (480°F) or the highest setting. Place a large baking sheet inside to heat.

Divide dough into two equal portions. On a well-floured surface, roll each portion paper-thin (almost translucent) into rectangles roughly 30x40cm.

Remove hot baking sheet from oven and brush generously with olive oil. Carefully transfer one dough sheet onto the pan.

Tear stracchino cheese into small pieces and distribute evenly over the dough, leaving a 1cm border around edges.

Drape the second dough sheet over the cheese filling. Press edges firmly to seal, then pinch and crimp decoratively. Poke several holes in the top with a fork.

Brush the top generously with remaining olive oil and sprinkle with flaky sea salt.

Bake for 12-15 minutes until golden brown and blistered in spots, rotating halfway through for even cooking.

Remove from oven and let cool for 2 minutes. Cut into squares or wedges, garnish with fresh rosemary if desired, and serve immediately while cheese is still molten.