Take the milk out of the refrigerator and let it sit at room temperature for 15 minutes before starting the recipe.
Melt the butter in a saucepan over low heat or in the microwave in 15-second intervals until almost fully melted.
In a large bowl, combine the milk and melted butter. Use a hand mixer or stand mixer to whisk until the mixture begins to thicken. Once combined, allow the mixture to cool in the fridge for at least 5 minutes.
Add the powdered sugar and vanilla extract to the mixture. Whisk again, using the mixer, until the mixture is smooth and creamy, and soft peaks form.
Use the whipped cream immediately, or store in the refrigerator for up to 2 hours before serving.