First, make the cake. Preheat oven to 350F and spray two 6" round cake pans with nonstick baking spray.

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 flavoring, and add them to the dry ingredients. Mix until combined.

Pour in the nondairy milk, and mix until combined. Finally, stir in the chopped pistachios and chocolate.

Divide batter evenly among the 2 pans, and bake for 35-40 minutes until cake is set in the center and a toothpick comes out clean.

When ready to assemble, make the frosting. In the bowl of a stand mixer fitted with the paddle, beat together the shortening and vegan butter until smooth and creamy. Add in the pistachio icing.

Mix in the powdered sugar ½ cup at a time until a thick frosting forms. It is normal to have to add 2-3 tablespoon of milk to get the frosting to the right consistency. You want it to be soft but still hold its shape.

To assemble, first cut the cakes in half diagonally to create 4 cake layers. Place 1 layer down on a cake board or plate, and top with some frosting. Repeat with all.

Be sure to set some frosting aside if you want to use it for decorating the top (or you can make another ½ batch if needed). Use the rest of the frosting to coat the outside of the cake.

Finally, make the ganache. Combine the chocolate chips with 1-2 tablespoon of the nondairy milk in a microwave safe bowl. Heat in 20 second increments, stirring in-between, until chocolate is melted and smooth. Add more non-dairy milk as needed until ganache is smooth, shiny, and thin enough to easily run off a spoon.

Decorate the top as desired with the ganache. I like using a squeeze bottle for easier decorating.

Let the cake chill for 10-15 minutes so the ganache can set, then you can decorate the top with the reserved frosting. I used a 1M tip to make the fluffy dollops. Finish off the cake with desired sprinkles. Enjoy immediately, or refrigerate until ready to serve.