Preheat oven to 350 F. In a large bowl, whisk together flour, sugar, cocoa powder, salt, baking powder and baking soda. Add in eggs, milk, vegetable oil and vanilla extract, and whisk until smooth.
Pour the cake batter into a large greased baking dish. Bake for 35-45 minutes. Let cool completely.
For the chocolate buttercream frosting, beat softened butter with powdered sugar, milk, vanilla extract an cocoa powder until smooth. Frost cooled cake and sprinkle the crushed oreos on top.
Decorate with the milano cookies and gummy worms.
