Chocolate Cake Ingredients:
2 cups all-purpose flour
2 cups white sugar
1/4 tsp. salt
4 heaping Tbsp. cocoa powder
1 cup (2 sticks) unsalted butter
1 cup boiling water
1/2 cup buttermilk - Make your own buttermilk by combining 1/2 Tbsp. of white vinegar with enough milk to make 1/2 cup
2 eggs, lightly beaten
1 tsp. baking soda
1 tsp. vanilla extract
1/2-1 cup chocolate cookie crumbs
Preheat the oven to 350 degrees F and place the rack in the center of the oven. Lightly spray a large sheet pan with non-stick cooking spray or grease with butter. Sheet pans almost look like cookie sheets, but have a higher lip around the edge so the batter doesn't spill over.
In a large bowl, whisk together the flour, sugar, and salt. In a medium saucepan, melt the butter over medium heat. Add the cocoa powder to the melted butter and whisk to combine. Add the boiling water to the butter and cocoa mixture, allow it to boil for 30 seconds, then remove from the heat. Pour the chocolate over the flour mixture and stir to combine. Set aside to cool slightly.
In a separate, small bowl, combine the buttermilk, eggs, baking soda, and vanilla. Stir the buttermilk mixture into the chocolate mixture and stir until thoroughly combined. Pour the batter into the prepared sheet pan and evenly smooth the top with a rubber spatula.
Bake for 15-20 minutes, until a toothpick inserted into the center of the cake comes out clean. Keep the cake in the pan and transfer to a wire rack to cool completely before frosting and decorating.
*Chocolate cake recipe adapted from The Pioneer Woman
Chocolate Mousse Icing:
3/4 cup unsalted butter, room temperature
3 Tbsp. cocoa powder
4-5 Tbsp. whipping cream
1 tsp. vanilla extract
3-4 cups icing sugar
In a large bowl, cream the butter with an electric mixer until it is soft. Add in the cocoa powder, whipping cream, and vanilla and mix on low speed until combined. Mix in the icing sugar 1 cup at a time until it reaches a fluffy, mousse-like consistency. If you end up adding in too much icing sugar then add in a bit more whipping cream to smooth it out, and if you add too much whipping cream just add in a little more icing sugar to stiffen it back up.
Evenly spread the chocolate mousse icing over the cooled chocolate cake. Sprinkle the chocolate cookie crumbs over the icing until covered. Cover the cookie crumbs with gummy worms. I left some worms sitting on top of the cake and pushed some into the icing and cookie crumbs so they looked like they were combine out of the cake. Cut into squares and serve. Cover and store leftover cake in the refrigerator.