Heat the oven to 200C (400F/gas mark 6). Line a muffin tin with 6 paper cases (or 8 if making medium muffins).
In a large bowl, whisk together the dry ingredients: flour, oats, baking powder, bicarbonate of soda, salt, black pepper, dukkah, and half the nigella seeds.
In another bowl, whisk the wet ingredients: eggs, yogurt, and oil, until smooth.
Pour the wet mixture into the dry ingredients and stir gently until just combined – don’t overmix.
Fold in the grated courgette, then add the feta cubes, being careful not to crush them.
Divide the batter evenly among the muffin cases, sprinkle with the remaining nigella seeds, and bake for about 18 minutes (15–16 minutes for medium muffins), or until a skewer inserted into the center comes out clean.
Cool for a few minutes in the tin, then transfer to a wire rack. Serve warm or at room temperature.
