Turn on your oven and warm it up at 170 degree Celsius. Cut the butter into little pieces, then put all the ingredients in a bowl and mix. If the milk isn't enough (if the dough is too hard for you to mix), just feel free to pour in more milk.
Get out your rectangle-ish baking form and oil it with butter (you know, so that the cake will come out of that form easier).
After the dough is mixed (it doesn't matter that much if you couldn't get the butter all smooth - it'll melt anyways) put it into that form.
Put it into the oven and bake for about 60 minutes.
There you go - very easy and very good :)
*TIP: Use toothpicks after the 60 minutes to see if the cake is done or not. If there's dough around the pick, you know it's not done. If the pick is "dough-free" your cake is done.