Step 1: Prepare the Pastry Cream

1. Heat the milk: In a medium saucepan, heat the milk over medium heat until it begins to steam but doesn’t boil.
2. Mix the egg yolks: In a separate bowl, whisk together the egg yolks, sugar, and cornstarch until smooth and pale yellow.
3. Temper the egg yolks: Slowly pour about ½ cup of the hot milk into the egg yolk mixture, whisking constantly to prevent the eggs from scrambling.
4. Cook the pastry cream: Pour the tempered egg mixture back into the saucepan with the remaining milk. Cook over medium heat, whisking constantly, until the mixture thickens and begins to bubble. This should take about 3-5 minutes.
5. Add butter and vanilla: Remove the saucepan from the heat and whisk in the butter and vanilla extract until smooth.
6. Chill the pastry cream: Transfer the pastry cream to a bowl, cover with plastic wrap (press the wrap directly onto the surface to prevent a skin from forming), and refrigerate for at least 1 hour.

Step 2: Prepare the Rolls

1. Hollow out the rolls: Using a small knife, carefully cut a small circle out of the top of each Hawaiian roll, creating a “lid.” Gently scoop out a bit of the bread from the center of each roll, being careful not to tear through the bottom or sides. Reserve the tops for later.
2. Set up the rolls: Arrange the hollowed-out rolls on a serving platter or baking sheet, ready for filling.

Step 3: Fill the Rolls with Pastry Cream

1. Transfer the cream: Once the pastry cream is chilled, transfer it to a piping bag fitted with a round tip (or use a zip-top bag with a corner snipped off).
2. Fill the rolls: Pipe the pastry cream into the hollowed-out center of each roll until it’s just full. Place the reserved “lid” back on top for a neat presentation, or leave them open if desired.

Step 4: Make the Chocolate Glaze

1. Heat the cream: In a small saucepan, heat the heavy cream over medium-low heat until it just begins to steam.
2. Melt the chocolate: Place the chocolate chips in a heatproof bowl. Pour the hot cream over the chocolate and let it sit for 2-3 minutes to melt.
3. Add butter and corn syrup: Add the butter and corn syrup to the bowl, then whisk until the glaze is smooth and glossy.

Step 5: Glaze the Rolls

1. Drizzle or dip: Spoon the chocolate glaze over the tops of the filled rolls, or dip the tops directly into the glaze for a thicker coating.
2. Let the glaze set: Allow the rolls to sit at room temperature for about 10 minutes to let the glaze set slightly.

Step 6: Serve and Enjoy

1. Garnish: If desired, dust the rolls with powdered sugar, add a dollop of whipped cream, or garnish with fresh fruit.
2. Serve: Serve the rolls immediately, or store them in the refrigerator until ready to eat. Enjoy chilled or at room temperature.