In a mixing bowl, combine eggs, ham, milk, peas, sweetcorn, salt and pepper. Beat well.
Heat skillet on medium and melt butter. Pour egg mixture into skillet. As the omelette begins to set, lift up edges with a spatula so the uncooked portion of egg can flow under the cooked portion. Cook without stirring, shaking the pan occasionally to prevent sticking, until the mixture is set and underside is golden and cooked.
Place a plate over the frying pan, eating side down. Flip the pan to transfer the omelette to the plate cooked side up.
Add a dash of oil or cooking spray to the saucepan and slide the omelette back into the pan. Cook for 4-5 minutes until browned on the second side. Serve and enjoy!