adapted from Our Best Bites
2/3 cup granulated sugar (NOT powdered sugar)
1/3 cup flour
3 Tb. unsweetened cocoa powder
dash salt
1 cup milk
1 tsp. vanilla
1 cup butter, softened (no substitutions!)
1 cup semi-sweet chocolate chips
1.In medium saucepan, combine sugar, flour, cocoa powder and salt. Slowly add milk, whisking to combine completely (slowly adding the milk helps prevent lumps so don't be tempted to add it all at once). Heat over medium heat, stirring constantly, until thickened (about the consistency of a pudding). Remove from heat and stir in vanilla. If there are any lumps, push through a fine mesh strainer to remove lumps. Cool completely (I normally make this the day before or at least a couple of hours before and refrigerate until ready to use).
2. Melt chocolate chips in microwave for 30 seconds. Stir, then heat for 30 more seconds. Stir until completely melted, then refrigerate until chocolate is room-temperature (if it is hot at all it will melt the butter and leave you with a melty, gooey mess--delicious, but not good for frosting). In stand mixer fitted with whisk attachment, beat butter until creamy, about 1 minute. Add the flour/sugar/milk mixture and beat for 2 - 3 minutes or until combined and fluffy. Add cooled melted chocolate and beat until smooth and fluffy. Pipe onto cupcakes or cake.
Makes enough to generously frost 24 cupcakes or a 2-layer 8 or 9 inch round cake.