This a foolproof homemade frosting, sturdier than traditional buttercream and a lot easier than any of the meringues. You have to make it in two stages, so give yourself some time to let it cool before you whip it again!
You'll need:
- 1/2 c flour
- 1 3/4 c sugar
- 1 pinch salt
- 2 c milk
- 1 Tbs vanilla
- 1 lb (4 sticks) butter, at room temperature
First, make the roux. In a medium saucepan, whisk together the flour, sugar, and salt. (Some recipes have you add the sugar later, but this makes sure the frosting isn't grainy when you're done.) Add the milk and vanilla, and heat over medium heat, stirring constantly so the milk doesn't stick to the bottom. Bring it to a boil, at which point it will thicken quickly. You want it to be like a thick pudding. (If the roux doesn't cook to this point, it won't come together later.) Remove from heat and move to a bowl. Cover with plastic wrap so a film doesn't develop on the top, and refrigerate to cool it down. You can also cool it on the counter, but it will take a while.
Bring the roux and the butter to room temperature before you do the final whip. Start by whipping the butter until it's light and fluffy, scraping the side as you go if needed to make sure there are no chunks left. Then using a regular spoon, add the roux little by little, continuing to whip on medium the whole time, until it's all incorporated.
You can use an icing knife to frost a cake, or add it to a pastry bag for piping. For cupcakes, I add the frosting to a freezer bag, then cut off a corner in an X shape and pipe it like that.