Preheat fan oven to 180 degrees. Using a cake tin (I use a 10 inch square tin) line with some baking/parchment paper. In a large mixing bowl add all the dry ingredients - flour, baking powder, salt, sugar, mint, chopped onions, parsley, olives and halloumi. In another bowl add the wet ingredients - olive oil, milk and eggs. Using a spatula gently mix/fold the ingredients altogether. Transfer to the tin and use the spatula to even the dough. Finely grate the remaining hellim over the top and sprinkle over the nigella and sesame seeds. .