First, make the cake. Preheat oven to 350F and spray three 6" round cake pans with nonstick baking spray. Place 5-6 cookies in the bottom of each pan.

In a small bowl, whisk together the ground flaxseed with the water and set aside to thicken.

In the bowl of a stand mixer, combine the flour, baking powder, baking soda, salt, and sugar.

Add in the vegan butter, and beat on low until it's incorporated and has a sandy texture.

In a small bowl, whisk together the oil, flaxseed mixture, nondairy yogurt, and vanilla extract, and add them to the dry ingredients. Mix until combined.

Pour in the milk, and beat on medium-low until smooth and creamy. Finally, toss in the instant coffee and the sandwich cookies, roughly crushed with your hands. Mix a few times to combine.

Divide batter evenly among the 3 pans, and bake for 35-40 minutes until cake is set in the center and a toothpick comes out clean.

While the cakes bake, prepare your pudding. In a small nonstick pot, combine the nondairy milk, sugar, cocoa, and cornstarch. Turn heat onto medium, and cook the pudding, whisking often, until it starts to thicken. This will take a good 8-10 minutes. Once the mixture starts to boil and thicken, whisk constantly to prevent lumps. Then remove from heat, and stir in the vanilla and pinch of salt. Allow the pudding to cool completely before using for the cake.

Next, you can make the frosting. In the bowl of a stand mixer, beat the shortening, vegan butter, and vanilla extract together until completely smooth and creamy. Add in the cocoa powder, followed by the powdered sugar, 1 cup at a time, until a thick frosting forms. Add in the salt. It is normal to need to add 1-2 tablespoon of milk to get the right consistency. Add in the black food coloring.

To assemble the cake, first trim the tops of the cakes if needed.

Place one cake on your cake stand or platter (Oreo side up), and spread a thin layer of the black frosting on top. Spoon some frosting in a piping bag, and pipe a "fence" of frosting around the edge of the cake. This will keep the pudding from leaking out. Spoon your cooled pudding in the center. Top with the second cake, and repeat. Finally, stack the third cake on top.

Use the remaining frosting to completely cover the cake, making sure to fill any gaps. Smooth the frosting out with a bench scraper. It doesn't have to be perfect, as we will cover the cake with cookie crumbs shortly! Just be sure that the frosting is thick enough so that the cake does not show through.

Once the cake is fully frosted, we want to immediately cover it with cookie crumbs (before the frosting hardens). Crush about 10 Oreo cookies (either with a food processor or in a zip-top baggie with your hands/a rolling pin). Holding your cake with one hand, grab handfuls of the Oreo crumbs and gently press them to the sides of the cake. I find it easiest to do this over a large shallow bowl or baking sheet to catch all the extra crumbs. Do this until all the sides of the cake are covered. The top will be covered in pudding so it's ok if you don't cover it with crumbs.

Set the cake in the fridge to harden until almost ready to serve.

To finish assembling the cake, grab your vegan gummy worms. Using a small knife, gently twist it into the side of the cake to create a small hole and place a gummy worm inside. Repeat as many times as you'd like. Finally, spoon your remaining chocolate pudding on top of the cake and allow it to partially drip onto the sides of the cake. Top the cake with more gummy worms and crushed cookie crumbs. You're finished! Enjoy immediately, or store in the fridge until ready to eat.