Preheat your oven to 400°F (200°C).
In a large mixing bowl, whisk together the all-purpose flour, baking powder, salt, and sugar until well combined.
Add the warm water and 1/4 cup olive oil to the dry ingredients. Stir with a wooden spoon until a sticky dough forms.
Lightly flour a clean surface and turn the dough out onto it. Knead gently for about 1-2 minutes until the dough is smooth and cohesive. Avoid over-kneading.
Transfer the dough to a greased 9×9-inch baking pan and press it out evenly to cover the bottom.
Use your fingers to create dimples all over the surface of the dough.
Drizzle about 1 tablespoon of olive oil evenly over the dough.
Sprinkle the dried rosemary, garlic powder, and coarse sea salt over the top.
Bake in the preheated oven for 20-25 minutes or until the focaccia is golden brown and cooked through.
Remove from the oven and allow to cool slightly before slicing and serving.