1. In a medium saucepan,combine the flour, sugar and salt.
2. Add the vanilla and milk and turn the flame on medium heat.
3. Stir the mixture constantly until it reaches a boil. Cook for an additional 2 minutes, or until the mixture thickens up into a pudding-like consistency
4. Remove from the heat and transfer to a bowl. Place a layer of plastic wrap on top, making sure that the plastic is touching the mixture so that it doesn’t form a skin and cool to room temperature
5. Cream the butter using an electric mixer until pale and fluffy
6. Add in the cooled mixture one spoonful at a time until completely combined.
7. Whip the frosting until the consistency is fluffy and light.