Boil a pot of salted water and toss in the green beans and chopped onion. Cook for 3 minutes and transfer into a bowl full of water and ice. Let them sit there for about 5 minutes and strain. Pat them dry with paper towel or a clean kitchen towel.
Preheat the oven to 190C (374F).
Whisk the eggs and mix them with olive oil and milk.
Add in salt and black pepper.
Combine these with cornmeal and 2 tablespoons of cheese.
Fold in green beans and onion and stir until combined well.
Grease a baking pan and pour the mixture in it.
Bake for about 40 minutes, take it out and top with remaining 3 tablespoons of cheese and put it back in oven. Cook for another 5 minutes until the cheese topping melts a little and gets golden.