Mix the dry ingredients - Add the salt to the flour in a large mixing bowl and stir to combine.
Activate the yeast - In a jug, mix the lukewarm water with the olive oil, yeast and sugar. Stir well and leave for a minute to start activating.
Make the dough - Pour the wet ingredients into the flour and mix until you have a shaggy dough.
Knead - Tip the dough onto a lightly floured work surface. Knead for 8–10 minutes, adding a little flour as needed to stop it sticking. The dough should feel soft and slightly loose.
First prove - Place the dough into a clean, lightly oiled bowl. Cover with a damp tea towel or cling film and leave to prove for 1–2 hours, or until doubled in size
Prep the trays - Oil and lightly flour two baking trays
Shape - Knock the air out of the dough and turn it onto the work surface. Cut it in half, then gently stretch or roll each piece to fit the trays. Transfer the dough to the trays and spread it to the edges.
Second prove - Leave the dough to prove again for 30–40 minutes, until puffed and doubled in size.
Top the focaccia - Press olives deep into the dough. Drizzle generously with extra‑virgin olive oil. Finely chop the rosemary and sprinkle it over the top, followed by a pinch of sea salt.
Bake - Bake at 190°C for around 20 minutes, or until golden and crisp on top.
Cool & serve - Leave the focaccia to cool in the trays. Slice and serve warm or at room temperature.