Yes, you can make instant mashed potatoes without milk. You can use something as simple as water and add more butter or margarine to intensify the flavor. The only change is a lack of creaminess, and the mashed potatoes may taste a little flat.
Top the instant mashed potatoes with cheese and herbs. Sprinkle a generous handful of shredded cheddar cheese, grated parmesan, or blue cheese crumbles. You can also mix in fresh chopped chives or parsley for a loaded baked potato flavor.
If you don’t want to add any milk but still need something to add to your mashed potatoes, try saving the starchy water that you used for boiling the potatoes. Adding in a few spoons of the starchy water will help bring the potatoes together, and as it is salted, it will also help to add flavor.
One difference is the texture — these milks usually have a consistency closer to low-fat or fat-free milks. Select a milk that would give good hints of flavor to the instant potatoes, like the almond or rice, pour the directed amount, then add a little more butter or margarine for texture.