Heat a medium sized sauce-pan or dutch oven over medium heat.
In a medium bowl, combine cornmeal with 1 cup of water and whisk vigorously, removing any lumps.
Add to cornmeal water to hot pan and whisk immediately and vigorously. It will bubble and quickly turn into a deep blue-ish purple hue.
Add remaining 3 cups of water, salt and piloncillo and continue to cook over medium heat for about 90 seconds, until mixture is thick and creamy and the piloncillo has melted and dispersed.
*Careful: this mixture is very hot (like lava), and will burn you if it gets on your skin.
After mixture has bubbled and thickened, remove from heat and whisk in 1 cup of cold milk. This step makes the drink creamy and cools the mixture so that you can drink it.
Serve immediately in mugs and top each with a dot of butter.