In a medium pot over medium heat add ½ cup heavy cream, ¼ cup + 2 Tbsp cocoa powder, 1 cup roughly chopped chocolate, 3 Tbsp sugar, ¼ tsp salt, and 1½ Tbsp butter.
Allow the mixture to melt, stirring to combine to form a rich, glossy fudge filling. It will be thick but still liquid, but will firm up slightly when it cools. Remove to a bowl or measuring cup to cool.
If refrigerating dough overnight, cover the fudge and allow to rest overnight. Once ready to assemble rolls, heat in the microwave for approx. 30 seconds or until fudgy again, then proceed with the next step.
Crush graham crackers to form about ½ a cup (approximately 3 sheets) of crumbs. Once the fudge has cooled slightly, mix in the graham cracker crumbs, reserving a tiny bit for garnish, as desired.