Mix together the flour and salt in a mixing bowl. Whisk together the warm water (110℉) and yeast in a glass measuring cup until the yeast is dissolved. Add the oil. Slowly add into the flour mixture while mixing to form a loose dough.
Turn onto a lightly floured counter and knead until a smooth dough forms - about 1-2 minutes of kneading. Shape the dough into a ball and place it in a bowl that has been well-greased with olive oil (seam side down). Cover with plastic wrap and let rise in a warm place for 40 minutes.
Grease the bottom of a 9X9-inch pan with 1 tablespoon of olive oil and sprinkle with ⅛ teaspoon salt. In a small bowl, mix together the remaining 2 tablespoons of olive oil, chopped rosemary, and diced garlic.
Once the dough has risen, lift out of the bowl and gently place in the prepared pan. Press the dough into the corners and use your fingers to make holes all around in the dough to create that classic focaccia look. Pour the olive oil/rosemary/garlic mixture over top and spread evenly around and into the holes. Sprinkle on the remaining ⅛ teaspoon of salt and grind ⅛ teaspoon of pepper on top. Cover and let rise for 20 minutes. Preheat the oven to 400℉ while the dough is rising.
After the dough has risen, bake immediately in the preheated oven for 18-20 minutes or until lightly golden on top. Remove from oven and let cool in the pan for about 10 minutes before transferring to a wire rack to finish cooling. Store in an airtight container at room temperature. Enjoy!