Preheat the oven to 200C/400F/Gas 6. Grease 23cm/9in square baking pan with melted butter.
In a large bowl, combine all the ingredients together except for the sweetcorn kernels. Mix until you have the consistency of a sponge cake batter, then add the sweetcorn.
Stir to combine thoroughly, then pour into the prepared baking pan. Bake for about 20 minutes in the top of the oven. (Alternatively, you can bake these in a muffin tray lined with paper cases.)
The cornbread is ready when it has a golden colour and is springy to the touch. Allow to cool slightly before cutting.