Chocolate Pastry Cream Recipe

Name: Chocolate Pastry Cream Recipe
Ingredients: 4 ounces granulated sugar (1/2 cup; 115g), plain or toasted; 1 ounce (3 tablespoons; 30g) cornstarch; 1/4 teaspoon Diamond Crystal kosher salt; for table salt, use half as much by volume; 1/4 teaspoon ground cinnamon (see note); Yolks from 4 large eggs, straight from the fridge (2 1/2 ounces; 70g); 2 cups (455g) whole milk; 4 ounces dark chocolate, about 70%, chopped (3/4 cup; 115g); 1 ounce unsalted butter (2 tablespoons; 30g), cut into 1/2-inch cubes; 1 teaspoon (5ml) vanilla extract