Peel and slice potatoes and chop spinach. In a pot put potatoes, spinach, peas and garlic add little water and a teaspoon of oil then cook till peas done, dry up water if there is any. Mash all together add corns. Braise onions in butter till pinkish brown add mashie, salt, pepper and milk then mix well.
Serve hot with barbequed/grilled/fried steak, fish or chicken.

NB: can keep mashie ready then braise when serving. Can add grated cheese too