Hot Fudge Sauce

This is the hot fudge I made for ice cream sundaes at Travis and Caitlin's reception. I couldn't figure out how much I needed and didn't want to run out (what's an ice cream sundae without hot fudge?) so I made batch after batch after batch. We didn't run out! I have a freezer full of hot fudge sauce, but maybe one day, years from now, I'll want to make some more. This is a very easy, delicious, no fail recipe!

1-1/2 C granulated sugar
1/2 C brown sugar, packed
3/4 C cocoa
1/4 C all purpose flour
1/2 t salt
1 can (14 oz) evaporated milk
1 C water
2 T butter
2 t vanilla

Combine sugars, cocoa, flour, and salt in saucepan. Add milk, water, and butter. Cook over medium heat, stirring constantly, until boiling. Cook 5 minutes longer. Remove hot fudge sauce from heat, cool, then stir in vanilla.