Peel and boil spuds like you would for mashed.
Peel and finely chop onion.
Heat oil in a large frying pan and add onion.
Cook for 8 to 10 minutes.
Peel and mince garlic, add to pan along with pork.
Cook for 5 minutes stirring often.
Mash spuds with butter and milk.
Season to taste.
Cover the bottom of an casserole dish with half of the mashed potato, then meat then spread or pipe on the remaining spuds.
Grate cheese, dot with butter and bake for 15 minutes at 425° F. or until the top is well browned.