3/4 cup (150 grams) granulated white sugar
2 1/2 tablespoons cornstarch (corn flour)
1/4 cup (25 grams) unsweetened cocoa powder (regular or Dutch-processed)
1/4 teaspoon salt
1 2/3 cup (400 ml) milk, divided (whole or 2% reduced fat)
1/3 cup (80 ml) heavy whipping cream (35-45% butterfat content)
3 large egg yolks
3 ounces (90 grams) semisweet (or bittersweet) chocolate, finely chopped
1 teaspoon pure vanilla extract
1 tablespoon (14 grams) unsalted butter, room temperature (cut into small pieces)