Place sweet potato and ½ cup of milk in a large microwave safe bowl. Cover tightly with plastic wrap and microwave on High for 6 minutes, or until soft. Roughly mash with a fork. Whisk in remaining milk and egg yolks

Place flour into a large bowl. Stir in sweet potato mixture to a make a thick batter. Add the fetta and season to taste

Whisk egg whites in a large clean bowl to soft peaks. Fold into batter

Working in batches, pour about 2/3 cups of batter (depending on size of waffle maker) onto a pre-heated non-stick round waffle maker. Cook until golden brown until waffle iron stops steaming, about 5 minutes

Meanwhile, heat the olive oil in a large non-stick frying pan over medium high. Crack eggs one at a time into hot pan. Cook for 2-3 minutes, until whites set and are crispy around the edges but yolk is still runny

Top waffles with spinach leaves, sliced avocado and fried eggs. Dollop over the harissa yoghurt and sprinkle with pepitas

To make harissa yoghurt, stir yoghurt and lemon juice together and season to taste. Swirl in the harissa