In bowl of electric mixer, combine the flour, yeast, sugar and salt using the dough hook attachment. Slowly add water, raise speed to medium and knead until dough comes together and is smooth and somewhat elastic, about 7 minutes.
Transfer to lightly greased bowl. Cover with plastic wrap and damp kitchen towel. Let rest in warm spot until doubled in size, about 1 hour.
Add potatoes to medium saucepan and cover with cold water. Bring to boil and cook until fork tender, about 15 to 20 minutes. Drain and return to pot. Mash together with butter, 1/4 cup sour cream, salt, pepper, granulated onion and granulated garlic. Set aside.
Preheat oven to 475°F. Line baking sheet with parchment paper, set aside.
Once dough has doubled, divide in half. Roll each half on lightly floured work surface into large rectangles, about 1/4-inch thick. Place on prepared baking sheet. Bake for about 10 to 15 minutes or until golden brown around the edges.
Spread flatbreads evenly with mashed potatoes and sprinkle with shredded cheese. Bake until heated through and cheese has melted, about 10 minutes. Remove from oven and top with crumbled bacon and fresh chives. Finish off with drizzle of remaining 1/4 cup sour cream. Serve immediately.