Make the Custard: In a medium saucepan, whisk together sugar, salt, and cornstarch. Gradually whisk in the heavy cream, milk, and egg yolks until smooth.

Cook the Filling: Place the saucepan over medium heat and cook, whisking constantly, for 5–7 minutes until the mixture thickens and begins to bubble.

Finish the Custard: Remove from heat and pour the mixture through a fine-mesh strainer into a bowl to remove any cooked egg bits. Whisk in butter pieces one at a time until melted and smooth. Stir in the vanilla extract.

Chill the Custard: Press plastic wrap directly onto the surface to prevent a skin from forming. Refrigerate for 3–4 hours or overnight until completely cold and thick.

Prepare the Rolls: Use the large end of a piping tip or a small knife to cut a deep hole into the side of each Hawaiian roll without piercing through the other side. Gently create a small pocket inside.

Fill the Rolls: Transfer the chilled custard into a piping bag (or zip-top bag with the corner cut). Insert into each roll and pipe custard until it slightly peeks out.

Make the Chocolate Glaze: Place chocolate chips and heavy cream in a microwave-safe bowl. Microwave in 20-second intervals, stirring between each, until smooth and fully melted.

Dip the Rolls: Dip the top of each filled roll into the chocolate glaze and allow excess to drip off.

Set the Glaze: Place the rolls on a parchment-lined baking sheet or wire rack and allow the glaze to set at room temperature for about 10 minutes before serving.