In a saucepan, combine the cream, syrup, sugar, and cocoa powder. Bring to a boil, reduce the heat, and let simmer for 5 minutes, stirring occasionally.
Remove the pan from the heat and stir in the chocolate, butter, salt, and vanilla. Once the chocolate and the butter have melted, strain the entire mixture to ensure that no pesky cocoa powder clumps remain.
Let cool to room temperature. If you are making this in advance, refrigerate until ready to use and then gently reheat on the stove or in the microwave until the hot fudge is pourable. Store in the fridge for up to 2 weeks.
For the salty sprinkles: Combine everything in a small bowl and mix well. Store in a small jar and sprinkle on ice cream, sugar cookies just before baking, puddings, hot cocoa, milkshakes, etc.
For the brûléed bananas and finished sundae:
Cut the banana half in half lengthwise. Sprinkle a thin, even layer of sugar on the flat surface of the banana. Use a kitchen torch to melt the sugar. Repeat the process, this time sprinkling a slightly thicker layer of sugar. Torch the banana again until all the sugar is melted and is deep in color. Use right away.
Add the vanilla ice cream to your favorite ice cream bowl (I know you have one). Top with the hot fudge then tuck those stunning, caramel-capped bananas alongside the ice cream. Add the sprinkles and a dollop of whipped cream.