Gather your supplies -- these are brazilian, but I'm sure you'll find similar ones at your local grocery store.
Put two tbsp of margarine (butter will work just fine) on a pan and put it to melt on high heat.
As soon as it melts, put four tbsp of cocoa powder and mix.
Put on the lowest heat and pour all the condensed mil. Mix.
It should look like this now.
Now that you've mixed it all, wait until the liquid gets thick (like in the pic) and turn off the heat.
Pour it somewhere else and wait until it cools down. I like to put in the fridge so it gets cold and a little bit thicker :)
Get a spoon and -- enjoy! :)
P.S.: as the name says, it's "pan brigadeiro". Not to be confused with the proper brigadeiro, which is a chocolate bonbon covered in sprinkles.
P.P.S.: it's really important that you wait until it cools down. It'll be really hot when you get it out of the heat. And that "cocoa powder" is not a powder of cocoa. It's a powder of CHOCOLATE ;-)
Like it? Have questions? Tell me in the comments! :D