5 Tablespoons flour
1 cup milk
1 teaspoon vanilla
1 cup butter, softened to room temp
1 cup granulated sugar
In a mixer, beat butter and sugar together until the butter is light and fluffy and the sugar granules are ground up and no longer crunchy.
Meanwhile, on the stove over medium to medium-low heat, whisk flour and milk together. WHISK, WHISK, WHISK. You must whisk the entire time, or you will end up with flour lumps, and all of your materials and effort will be wasted. As the mixture thickens, keep whisking, don’t give up. The desired thickness is more like creamy peanut butter, anything thinner will not set up right when combined with the butter/sugar. Remember, speed is not the essence here, bringing it together too quickly will result in a floury taste to the frosting, but slowly will give the pudding a chance to cook out the taste. Think of it as when you make gravy with a flour thickener, you must cook out the flour taste.
When thick, remove from heat and whisk in the vanilla. scrape into a shallow bowl and press plastic wrap directly down on top of the mixture, so that a crust does not form as it cools. I was in a hurry the last time I made this, and I kept it in the saucepan, applied my plastic wrap and placed the entire pot in a bowl of ice to cool down. You are only bringing the temp down to room temperature, not any cooler.
Add the cooled pudding to the beaten butter/sugar mixture and beat on high, scraping down the sides of the bowl. If it looks separated, you haven’t beaten it enough. It will have the appearance of whipped cream frosting when you are done.