Step 1: Preheat your oven to 350°F (175°C) and line two large baking sheets with parchment paper for the creepy crawly dirt cookies base.
Step 2: In a large bowl, cream together the softened butter and granulated sugar until light and fluffy. Beat in the egg and vanilla extract until well combined.
Step 3: Sift together the flour, cocoa powder, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until a stiff dough forms.
Step 4: Scoop tablespoon-sized balls of dough and place them on the prepared baking sheets, spacing them about 2 inches apart. Flatten slightly with the palm of your hand.
Step 5: Bake for 8-10 minutes. The creepy crawly dirt cookies should be set but still slightly soft in the middle. Let them cool completely on a wire rack.
Step 6: While the cookies cool, crush the chocolate sandwich cookies in a food processor or plastic bag until they resemble fine dirt.
Step 7: Once the creepy crawly dirt cookies are cool, spread a thin layer of chocolate frosting over the top of each cookie.
Step 8: Dip the frosted side of each cookie into the crushed cookie crumbs, pressing gently to ensure the ‘dirt’ adheres well.
Step 9: Cut the gummy worms in half or leave them whole. Press the worms into the frosting/crumb layer of the creepy crawly dirt cookies so they look like they are crawling out.