Bring the butter, sugar, water and vanilla to a boil.
Add the flour and stir constantly until it leaves the side of the pot and forms a ball.
Remove and cool.
Beat in 4 eggs, one at a time until smooth.
Drop by T. onto parchment lined cookie sheets
Bake at 400 degrees for 15 mins. Reduce to 350 for 15 mins more.
Remove and immediately make a small slit on the side with a sharp knife to let the steam escape.
Once cool, slice in half.
Pile some ice cream in the middle, drizzle on hot fudge and serve immediately!
