In a large saucepan, whisk the sugar and cornstarch together until well combined. Set aside.

In a separate large mixing bowl or measuring cup, lightly beat the egg yolks. Whisk in the heavy cream until well combined, then whisk in the milk.

Slowly pour the wet ingredients into the saucepan with the dry ingredients and whisk until fully combined.

Place the saucepan over medium heat and bring to a boil, stirring/whisking often (I recommend using a rubber spatula to scrape around the bottom and sides of the pan several times). Allow to boil for one minute; the mixture should be pretty thick at this point. Do not increase the heat or boil too long! This can cause the pudding to turn out grainy.

Remove from the heat and stir in the butter, one tablespoon at a time, then stir in the vanilla extract.

Strain the mixture through a fine-mesh strainer into a heat-proof bowl.

Cover with plastic wrap, placing the plastic wrap directly on the surface of the pudding to prevent it from forming a skin. Allow to cool to room temperature, about 2 hours, then refrigerate for 2 to 3 hours or until thoroughly chilled.

Serve as is, or top with whipped cream and your favorite toppings!