Pull out a stand mixer and add the warm water, sugar, and active dry yeast to the bowl. Allow the yeast to activate for at least five minutes.
Next, combine the bread flour, all-purpose flour, and salt in a separate bowl.
Insert the dough hook attachment, start the mixer at low speed, and slowly pour in the flour mixture.
Once it forms into a dough, slowly add the olive oil and let the mixer run for another minute or so.
Stop the machine, scrape down the sides of the bowl, and make sure everything gets incorporated.
Increase the speed to medium for 8 to 10 minutes until the dough no longer sticks to the sides of the bowl.
Transfer your focaccina dough to a clean glass bowl and grease it lightly with olive oil.
Cover the bowl with a kitchen towel and place it in a warm place for an hour or until it has doubled in size.
Once the dough has doubled in size, punch it down and fold it over a few times.
Transfer the dough to a greased rectangular baking tray. Use your hands to stretch and flatten the dough evenly and let it rise for another 45 minutes.
Meanwhile, preheat your oven to 425 degrees Fahrenheit.
Once the dough has been proofed once more, use your fingers to make indents in it.
Drizzle more olive oil and brush it evenly across the surface. Sprinkle the salt, olives, and rosemary on top.
Place the prepared black olive and rosemary focaccina in the oven for up to 25 minutes or until golden brown.
Once done, remove it from the oven, drizzle it with more olive oil and let it sit for 10 minutes, transferring the black olive and rosemary focaccina to a cooling rack once it is easy to handle.
Cut into small squares and serve it with your favorite pasta dish or charcuterie board.