In a separate bowl, evenly whisk together the milk and cornstarch until it's lump free.
Add the milk and cornstarch mixture to your eggs and beat until smooth. Season with salt to taste.
Heat a non-stick skillet over high heat until hot, then add the butter (should sizzle right away). Wait until the butter is melted and bubbly, but before it browns.
Add the beaten eggs. Wait for 3 seconds without stirring anything, until the edges of the eggs start to bubble up.
Then remove the skillet from the heat (yes, remove!) and start stirring the eggs, making 1 full circle per second - 1, 2, 3 . . . (if you use a mini skillet instead of a large one, it may need a few more seconds).
For about 11 or 12 seconds. The eggs will have absorbed all the butter, but remain partially undercooked (add about 5 seconds more to every 3 extra eggs you're scrambling).
This is when you transfer them onto a plate. Do not wait until they look fully cooked.