Heat 2 cups of whole milk in a saucepan over medium heat until the edges begin to steam but do not boil. In a mixing bowl, whisk together 4 egg yolks, 1/2 cup granulated sugar, and 1/4 cup cornstarch until smooth. Slowly temper the yolks by pouring the hot milk into the mixture while whisking continuously. Return this mixture to the saucepan and cook over medium heat for 3-5 minutes, stirring constantly until thickened. Remove from heat, mix in 2 tablespoons of unsalted butter and 1 teaspoon of vanilla extract, then let cool before chilling in the refrigerator for at least one hour.

While the pastry cream chills, prepare the Hawaiian sweet rolls by carefully hollowing them out. Using a small paring knife, cut a circular opening on the top of each roll and gently remove some of the soft bread inside, creating enough space for the filling. Place the hollowed rolls on a platter, keeping the tops of each roll nearby for easy assembly later on.

Once the pastry cream has chilled and thickened to a velvety consistency, it’s time to fill your hollowed Hawaiian rolls. Using a piping bag or a small spoon, generously fill each roll with the chilled pastry cream, ensuring each is packed full of goodness.

In a small saucepan over medium heat, heat 1/2 cup of heavy cream until it starts steaming, then remove it from the heat. Pour the hot cream over 1 cup of semi-sweet chocolate chips in a mixing bowl and let sit for a minute to soften. Whisk together until the chocolate is completely melted and smooth, then add 1 tablespoon of unsalted butter and 1 tablespoon of light corn syrup for a glossy finish, stirring until fully incorporated.

To finish your Boston Cream Pie Stuffed Hawaiian Rolls, dip or spoon the rich chocolate glaze over each filled roll, allowing the excess to drip off. Arrange the glazed rolls on a wire rack or a parchment-lined tray to set for about 10 minutes.

For a final touch, dust the tops of the rolls with powdered sugar and serve alongside whipped cream or fresh fruit, if desired.