Preheat the oven to 350 degrees F and grease four ramekins or muffin cups.
Melt the butter in a mixing bowl, then stir in the sugar until combined.
Add the eggs and vanilla extract and mix well.
Stir in the cocoa powder, flour, and salt until the batter is smooth.
Divide the batter evenly among the four prepared cups.
Bake for 20 to 25 minutes until the edges are set but the centers still look slightly soft.
Let the brownies cool completely in the cups.
Crush eight of the chocolate sandwich cookies into coarse crumbs and sprinkle them over the top of each brownie.
Press one whole chocolate sandwich cookie upright into the crumbs on each cup to form a tombstone.
Lay one gummy worm on top of the crumbs on each brownie cup.