Make and bake a box of brownies according to package directions.
While brownies are baking, place cream, corn syrup, brown sugar, cocoa, salt, and half the chocolate chips into a small saucepan. Place over medium heat and stir frequently until it comes to a boil. Reduce the heat to low and lightly simmer for 5 minutes. Remove from heat and whisk in remaining chocolate, butter, and vanilla. Pour sauce into a separate bowl to cool until brownies are done baking.
Once brownies are done baking, cool 5-10 minutes and poke holes into it. Drizzle 3/4 cup prepared hot fudge overtop brownies and spread to saturate evenly. Sit another 10 minutes or so, then cut into squares and serve with ice cream and cherries.