In a large bowl, whisk together flour, yeast, sugar, and salt.

Pour in warm water and olive oil, and mix with a spoon until a shaggy dough is formed.

Turn the dough out onto a clean work surface, and knead until a soft, smooth and elastic dough is formed - about 8-10 minutes.

Transfer the dough to a lightly oiled bowl, cover with a tea towel, or plastic wrap, and set aside until doubled in size, about 1 hour.

Once the dough has doubled, grease a 9x13 inch baking pan with oil and set aside. Punch down the dough and transfer to the baking pan, stretching into a rectangle to almost cover the entire bottom. Cover with a tea towel or place wrap and set the dough aside to rise for another 30 minutes or so.

Preheat oven to 400 degrees F.

Once the dough has sat for the 30 minutes, press the dough to the edges of the pan using your fingertips. Make sure you create little dimples with your fingers all over the top of the dough.

Arrange the olive and grape halves evenly across the top of the focaccia dough. Drizzle the dough with olive oil (I also like to use my pastry brush to ensure the olive oil is distributed evenly). Sprinkle with minced rosemary, if using.

Bake for 15-20 minutes, or until golden.

If desired, squeeze a little rest lemon juice over the top of the focaccia, and sprinkle with a little bit of malden salt - not too much though, as the olives are quite salty on their own. Once the focaccia has cooled slightly, remove from the pan and allow to cool completely on a cooling rack.