Instructions:
In a large microwave-safe bowl, whisk together the milk, sugar, cornstarch, and salt until well combined.
Microwave on high for 2 minutes, then stir. Repeat microwaving and stirring in 2-minute increments until the mixture thickens and comes to a boil.
Stir in the beaten egg, butter, and vanilla extract. Mix until the butter is fully melted and incorporated.
Pour the mixture into the pre-made pie crust.
Dust with cinnamon.
Microwave on high for 1 minute, or until the filling has set.
Allow to cool completely before slicing and serving. Enjoy!
