In a small bowl combine the warm water, yeast and sugar, stir to dissolve. Let sit for 12 minutes or until the mixture is nice and foamy.
In the bowl of a mixer fitted with a dough hook, combine the flour, potato flakes and salt. Add the yeast mixture and olive oil, mix on low speed until the dough comes together. Turn the speed to medium and continue to knead for 5-7 minutes. The dough should be smooth and soft. If the dough is too wet or tacky, add an additional tablespoon of flour and knead for 1 minute.
Transfer the dough to a lightly floured surface. Gently knead until a smooth ball forms.
In a large bowl (or a clean stand mixer bowl), add 1 tbsp. of olive oil. Use your hands to coat the bowl. Place the dough in the bowl, flip the dough over, then cover the bowl with plastic wrap. Let rise until doubled, about 1-1 1/2 hours.
Coat a 12" x 16" rimmed baking sheet with 3 tbsp. of olive oil. Place the dough onto the prepared pan and press/stretch it with your hands to fit the size of the pan. Once the dough is stretched, use your index finger to make impressions or dimples in the dough (don't poke all the way through, just go as far as you can without breaking through).
Cover the pan with plastic wrap let rise until doubled, about 1 hour.
Preheat the oven to 425 degrees.
Brush the top with the remaining 2 tbsp. of olive oil. Top with rosemary, garlic, and remaining salt.
Place in the oven and bake until golden brown, about 18-22 minutes. Remove from the oven and let it cool in the pan for 15 minutes. Transfer to a cutting board and cut as desired.