Heat oven to 120C/100C fan/gas 1/2. Grease a 20 x 20cm cake tin and line with baking parchment. Separate the eggs. Put the yolks in a food processor or blender with the sweetcorn and blitz to a rough purée. Tip the blended mixture into a large bowl and stir in the butter, cornflour, baking powder, sugar and 1/2 tsp salt. Mix thoroughly.
Whisk the egg whites until they have reached the stiff peak stage. Gently fold the egg whites into the corn mixture using a large metal spoon until completely incorporated, keeping as much air in the mixture as possible.
Spread the corn batter over the base of the tin with a spatula. Sprinkle over the cubes of cheese and push them into the mixture so they are almost completely covered.
Cook for 1 hr 45 mins until firm and golden and shrinking slightly from the sides. Remove from the oven and leave to cool for at least 15 mins before cutting into chunks and serving, scattered with olives. Leftovers will keep in the fridge until the next day.