In a large bowl, mix warm water, sugar, and yeast. Let it sit for 10 minutes until foamy.
Add flour, salt, and olive oil. Stir until a sticky dough forms.
Knead the dough on a lightly floured surface for 8–10 minutes until smooth.
Place in a greased bowl, cover, and let rise for 1 hour until doubled.
Punch down the dough and press it into a greased baking pan.
Dimple the dough with your fingertips, drizzle generously with olive oil, and sprinkle rosemary and flaky salt.
Cover and let rise again for 20 minutes while the oven preheats to 400°F (200°C).
Bake for 20–25 minutes until golden brown and fragrant.
Cool slightly before slicing and serving.