In a large mixing bowl, whisk together flour, baking powder and salt. Make a well in the centre then pour in most of your yogurt. Combine with a spatula until it comes together, then begin forming into a ball with your hands. It should be very slightly tacky, but not so much it sticks to your fingers. Add a pinch more flour if it's too wet, add a dollop more yogurt if it's too dry. The perfect consistency will take all the dough off the edges of the bowl.
Place on a floured surface and knead for a 4-5mins until completely smooth and lump free, adding more flour as needed. The kneading process will dry out the dough so don't add too much flour or it'll throw off the consistency. Cover and rest for 5-20mins (perfect time to prep toppings). Use a sharp knife to divide into 4 smaller portions.
One by one roll out each ball into a 7"x7" circle. Brush one side of each of them with olive oil (just enough to full coat the surface, around 1 tsp per side should be fine).
Heat a pan over medium-high heat and when hot carefully place a flatbread oil-side-down in the pan. Brush top with oil. Allow the dough to puff up and lightly char, then flip and leave to lightly char on the other side. Remove from pan and repeat (refer to notes).
Place flatbreads on a large tray (or two if you need to) and coat each with pizza sauce, then sprinkle with mozzarella. Finish with your toppings (see notes) then place under the grill and broil until golden and gooey. The flatbreads are already completely cooked, so baking is not necessary. It's only the toppings you need to cook.
Allow to rest for a few mins, they may be slightly soft at first, but they do firm up as they cool. Slice 'em up and enjoy!