In a saucepan over medium heat, sift together sugar, cocoa, and flour. Whisk in milk and egg yolks. Continue to cook, stirring often until mixture is very thick ( like pudding) about 20 minutes.
In a saucepan over medium heat, sift together sugar, cocoa, and flour. Whisk in milk and egg yolks. Continue to cook, stirring often until mixture is very thick ( like pudding) about 20 minutes.