Prepare one pizza at a time: Flip over a baking sheet, wrong-side up, and place a sheet of parchment paper on the baking sheet. Sprinkle 1 tsp of the flour and 1 tsp of the cornmeal on the parchment to coat evenly. Place a rolled-out circle of dough on top of the paper and drizzle with a little melted ghee. Spread out half of the tomatoes over the dough. Sprinkle with half the mozzarella and 1 Tbsp of the spices in the mortar. Slide the circle of dough onto the preheated baking steel, discard the parchment paper, and shut the oven door. Lower the heat to 425°F [220°C] and bake until the edges of the crust start to turn golden, 10 to 12 minutes. Garnish with half the chopped chives and flaky salt, and drizzle with a little extra ghee. Repeat with the remaining circle of dough and serve the pizzas hot.