Kip's Hot Fudge Sauce

This recipe belongs to one of Kip's old roommates--a guy I never knew named John--so, John, if you're out there, can I please post your recipe on my blog? Thank you.
Makes about 4 cups
Prep time: 2 minutes
Cook time: 15-20 minutes
Cost: $1.89 or $1.30 depending on type of milk used
(sugar: .32, cocoa: .25, butter: .50, evaporated milk--.79 on sale, (or regular milk: .20), other stuff: .03)

Note on evaporated milk: The original recipe called for evaporated milk. However, once when I was out of it I used regular milk--1 1/2 C and it worked just fine. (Also, I don't know how it would work with skim and therefore can't vouch for that.) I boiled the regular milk a bit longer, just to be safe and the sauce came out tasting the same. Using regular milk will knock $.50 off of the cost of this. However, today I had some evaporated milk getting close to its expiration in the pantry, so that's what I used.

2 C sugar
1/2 C cocoa
2 Tbsp flour
1/2 C (1 stick) butter
1 can evaporated milk
2 tsp vanilla

Put butter in saucepan and begin to melt.

In the meantime, sift together dry ingredients in separate bowl.

When butter is melted or close, add the evaporated (or regular) milk. Whisk together. Add dry ingredients and whisk together. Bring all ingredients to a gentle boil. Boil for 5 minutes (gently--this shouldn't be a crazy rollicking boil.) Remove from heat. This is perfect on ice cream or in dessert crepes or, frankly, eaten out of the container with the spoon. Not that we would do such a thing.

Serve warm (unless eating straight out of the fridge, in which case, cold is fine). Leftovers can be kept refrigerated for a couple weeks.