Melt the butter in the microwave for 30-60 second then mix the crushed garlic with it.
Finely chop the onion into the smallest cubes possible.
Remove the seeds and pith from the Jalapeno and finely chop.
Combine all of the ingredients in a large bowl being careful not to over mix - hold back half of the cheese for the topping.
Grease your baking tray (15"x10" recommended) with some butter then pour in the mixture and use a spatula to spread it evenly then top with the remaining cheese.
Bake in the oven for 30-40 minute and test if i skewer comes out clean to check if cooked through.