Preheat the oven to 200°C.
Add the corn to a food processor and pulse once or twice, just until roughly chopped. Transfer corn to a large bowl and add the spinach, polenta, parmesan, spring onion, coriander, parsley, dill, garlic, 1 ½ tsp salt and a good grind of pepper, and stir to combine.
Transfer this mixture to a large, deep, ovenproof frypan, then add the milk, stock and butter, stirring gently to mix through. Transfer to the oven and bake for 20 minutes, then remove from the oven and give everything a good whisk.
Return to the oven and bake until the polenta is cooked through and the mixture has thickened, about 20 minutes. Give the polenta another good whisk – it should be quite smooth and not completely set – then stir in half the feta. Increase the oven temperature to 220°C.
Use a dinner spoon to make 8 shallow wells in the polenta. Crack an egg into each well and sprinkle lightly with salt and pepper. Sprinkle the remaining 70g feta all over, and bake until the eggwhites are cooked and the yolks are still runny, 10-15 minutes.
Meanwhile, combine the extra spring onion, coriander and oil in a bowl. Spoon this mixture all over the polenta and eggs and sprinkle with the chilli flakes. Serve directly from the pan.
