Begin by blooming the yeast: add the sugar to the warm water and stir to dissolve. Sprinkle the yeast over top, gently stir, and let sit for about 15 minutes. The yeast will become frothy.
In a large bowl add the flour, salt, and 2 tbsp of olive oil
Pour in the yeast mixture and mix with a wooden spoon or spatula until combined. You can begin to mix by hand until a dough of ball comes together loosely
Turn the dough out onto a lightly floured surface and knead by hand for about 5 minutes. The dough should become elastic and smooth
Place the ball of dough into another large bowl greased with 2 tbsp of olive oil and turn the dough around to coat it in the oil. Cover with plastic wrap and let it rise for about 1 hour until it has doubled in size
When the dough has finished rising, preheat the oven to 400 degrees F. Grease a 9x13 inch baking sheet with 2 tbsp olive oil
Using your hand, lightly punch the center of the dough to deflate it. Use your fingers to stretch the dough out to the edges of the greased baking sheet and make indents using your fingers all over
Drizzle the dough with 2 more tbsp of olive oil and sprinkle with rosemary and flaky sea salt
Bake in preheated oven for 25 minutes or until golden and puffed up