Very few foods receive the appellation of "Perfect" in my household (Perfect Brownies being one of the few), but this truly is.
Perfect Fudge Sauce:
Combine 1/4 cup cocoa (I use Hershey's from the market), 1/2 cup sugar, 1/2 tsp. salt, and 2 T. flour in a small saucepan. Add 1/2 cup light corn syrup and 1/2 cup milk. Bring to a boil, stirring occasionally, then let mixture boil for 5 minutes without stirring. Remove from heat. Stir in 2 T. butter and 2 tsp. good quality vanilla (the Spice House has amazing Madagascar vanillas). Let cool until slightly warm.
Scoop up a few spoonfuls onto a bowl of vanilla ice cream, and the world is suddenly a much better place.