Preheat the oven to 350°F and line an 8x8 pan with parchment paper. In a mixing bowl, stir together the melted butter and sugar until smooth.
Add the eggs and vanilla extract, then mix until fully combined. Stir in the cocoa powder, flour, and salt until no dry streaks remain.
Pour the batter into the prepared pan and bake for 20 to 22 minutes, until the center is just set. Let the brownie cool completely in the pan.
Sprinkle the crushed chocolate sandwich cookies evenly over the cooled brownie to create the dirt layer. Press the shortbread cookies upright into the topping to stand as tombstones.
Tuck the gummy worms into the crushed cookies so they appear to be coming out of the dirt. Slice into four pieces and serve.