Combine baking powder and 3 1/2 cups flour in a large bowl. Make a well in centre. Add yoghurt, zucchini, cheddar and herbs. Mix to form a shaggy dough. Dust workbench with remaining flour. Knead dough for 1 minute or until a smooth dough forms. Transfer to a clean bowl. Cover and rest for 20 minutes.
2 1/2 tsp baking powder, 3 3/4 cup wholemeal plain flour, 1 cup reduced-fat plain yoghurt, 1 medium zucchini, 50 g cheddar, 1 bunch chives, 1/4 cup oregano leaves