In the bowl of your stand mixer, combine the tepid water and yeast. Stir to combine. Once the yeast has dissolved in the water, add 2 tablespoons of olive oil. Secure the bowl on your mixer and using the dough hook attachment, start the mixer on low and add the flour gradually. Continue to knead on low for 5 minutes, adding a touch more water, if required, until all the flour has been incorporated and you have a smooth dough. Add the salt during the last minute of kneading.
Using your hands, form the dough into a ball and place in an oiled bowl. Cover with plastic wrap and leave to rise for two hours or until the dough has doubled in volume.
Turn the risen dough out onto a floured surface. Knead in chopped rosemary until it is uniformly spread throughout the dough.
Preheat the oven to 400˚F. Grease a 9-inch round or square baking tray with the remaining tablespoon of olive oil. Flatten the dough on the tray and leave to rise for 1 hour. Using your fingers, make indents all over the flattened dough. Drizzle with some more olive oil and sprinkle kosher salt all over. Bake in the oven for approximately 15-20 minutes or until the focaccia is golden on the top and bottom. Best enjoyed while warm.
You don’t need a stand mixer to make focaccia. Simply mix together the ingredients in a large bowl and use your hands to combine and knead.