Gather all your ingredients together.
Place sugar, flour, and salt into a medium pan. To combine.
Add milk and vanilla to the sugar mixture, and stir to combine. Cook over medium heat, stirring constantly until the sugar dissolves and the mixture boils. Continue cooking while stirring constantly for one to two more minutes until the mixture thickens to a pudding-like consistency.
Pour into a bowl and place plastic wrap directly on top of the mixture to prevent skin from forming. Allow the mixture to cool to room temperature.