Chocolate cream:

• Bring the 1/2 cup of heavy cream to a boil and remove from the heat as soon as it starts to simmer
• Pour over the chopped chocolate in a bowl, and cover for 5 minutes. Then stir gently until it forms a smooth, shiny ganache. Let cool for 10 minutes
• In a separate bowl, whisk the 2/3 cup cold heavy cream until it reaches the stiff peak stage, taking care not to over mix
• Add the whipped cream to the ganache in 2-3 additions, gently folding between each. Take care not to knock out the air. This will form a mousse like chocolate cream
• Refrigerate for 20 min or as long as needed until the cream reaches a pipeable consistency

Assembly:

• Separate the rolls and place on a wire rack
• Use a large serrated knife to place a cut down the middle of each roll; it should go about 80% of the way such that it is quite deep but the roll is not cut into half
• Transfer the chocolate cream to a piping bag and cut a medium sized hole in it
• Hold the roll in your hands, pulling it open carefully with your fingers as widely as you can without breaking it. Use the other hand to pipe a generous amount of the chocolate cream in the middle. Use a palette knife to press down the cream while still holding the roll open, and smooth out the top. Use your fingers to clean up the edges as needed, and place back on the wire rack
• Repeat until all rolls are filled
• Place in the fridge while you make the glaze

Chocolate glaze:

• Add the butter and chocolate to a microwave safe bowl, and melt in the microwave in 15 second increments until the create a shiny glaze. It should be warm and runny but not too hot
• Remove the filled buns from the fridge
• Pick up one bun from the side and carefully dip the other side into the chocolate glaze at an angle. Lift and shake off any excess, then place back on the wire rack
• Repeat until all buns are coated in the glaze on one side
• Optionally, sprinkle over some chopped chocolate or chocolate sprinkles
• Serve & enjoy!