Boil cabbage in water for about 15 minutes. Drain and set cabbage aside. In a new pot of water, boil the potatoes until tender and drain off water.
In a sauce pan, sauté leeks in milk, bring to an almost boil and then simmer until tender.
Add mace, salt and pepper, garlic and butter to the potatoes and mash well (use a hand masher), no add the leeks and milk to the mix. Stir tenderly, you don’t want to break this into a mush. Add cabbage, continue to stir until it’s smooth with nice toothy bits of cabbage.
Transfer this to a 10×13 Pyrex dish, put under the broiler. Score a cool design in the top with a fork (serves no purpose other than the “ooh ahh!” factor) and broil until browned on top.
This dish is FANTASTIC. If you are tired of mashed potatoes, or even mac and cheese (gasp!) this could be your next comfort food. It goes fantastically during the holidays with a rib roast just as much as you can do meatloaf on Thursday. Enjoy!