Cut the butter into 1-inch chunks and melt it over the stovetop or in a microwave. (If you use a microwave, make sure you heat it at 10 seconds intervals and check on it before adding another 10 seconds else it will splatter everywhere and it'll get messy :) ). Set the melted butter aside.
Use a 9-inch pan and butter it or line it with parchment paper. It's important that you use a pan that is 9-inches or larger with a height of at least 2 inches so that the chocolate filling doesn't overflow or get too high - which will reduce the amount of crispy phyllo exposed by half.
Get a large kitchen towel or some paper towel and wet it. Wring it out really well so that it is just damp. Remove the phyllo pastry from the packaging and place it closeby on the counter, folded in half and cover it with the damp towel.
Take 1 sheet of phyllo pastry and brush it liberally with melted butter. Take another sheet of phyllo pastry and lay it on top of the buttered one and brush melted butter on it liberally as well.
Gently pinch the pastry into ruffled folds on the 2 ends and the middle.
Gently spiral it into a coil and tuck the end underneath the bottom so that the bundles sit higher (this is to expose more of the phyllo pastry during baking for more crispiness!) I like to also gently pull up the middle of the coil as well to make it sit slightly higher.
Set the bundle in the pan.
Continue steps 4-7 until you have 5 bundles in the pan. Make sure to leave a small space where you can cleanly pour the chocolate filling in without getting it on top of the ruffled bundles.
Use the remainder of the butter and brush the tops of each phyllo bundle until there is a light layer of butter on it. You may need to heat up some more butter if there is not enough.
Pre-heat the oven to 350F (180C).
Put it in the oven and bake it for 25-30 minutes until it is slightly golden and crispy at the tops.
Remove it from the oven and let it slightly cool while you make the Black Sesame Chocolate Filling. (Leave the oven on, we will still need to use it.)