Heat oil, let crack the ajwain seeds, add the chopped onions, chopped green chillies, saute everything for few minutes, add immediately the chopped spinach leaves, cook for few minutes. Now add the mashed potatoes, garam masala powder and salt, cook everything in simmer for few minutes, put off the stove. Keep aside and let them cool.
Take the wheat flour in a large bowl with salt, gradually add the hot milk and water, knead everything as a soft dough, keep aside for half an hour. Make a lemon size balls from the dough, dust with all-purpose flour, roll them as a small disc, place a medium sized ball of already prepared aloo palak masala, seal the edges together, roll them as parathas by dusting with all-purpose flour and rolling gently.
Heat a tawa, drop gently the stuffed aloo palak paratha, drizzle a few drops of oil, cook on both sides in medium flame until they get cooked well. Enjoy hot.