Cream the butter on medium until soft. Add the sugar and beat until light and fluffy 5-7 minutes.

In a saucepan, combine 1/4 cup of milk, flour, and vanilla and whisk until no lumps. Over medium heat, add the remaining milk while whisking constantly. Cook until a low boil. Reduce the heat to low and continue whisking until the mixture starts to thicken.

Remove the pan from the heat and continue to stir. Once it has thickened and cooled slightly, you may place it in the freezer to cool faster.

Using the mixer at low speed, slowly add the milk mixture into the butter mixture. Increase to medium speed and beat until light and fluffy 3-5 minutes.

Chocolate buttercream: Can add 4 ounces melted dark chocolate while the milk mixture is cooling. Add the cooled chocolate to the milk mixture and add to the butter mixture.