In the large bowl of an electric mixer, or using a hand-held mixer, beat the 1 cup of unsalted butter or vegan baking stick until smooth and creamy, about 2 minutes.

With the mixer on low speed, gradually add the 6 cups of confectioners' sugar, 1 teaspoon of vanilla, and the pinch of salt.

While the mixer is running, slowly add the water, a little at a time, until you reach the desired consistency. You may not need to use all of the water.

Once all ingredients are incorporated, increase the mixer speed to medium-high and beat for 2-3 minutes, or until the frosting is light, fluffy, and creamy. Set aside.

Place 5 of the sandwich cookies into a zip-top bag and seal it. Crush the cookies with the flat side of a meat mallet or rolling pin until they form a sand-like consistency.

In a large bowl, whisk together the 1.5 cups of gluten-free flour, 1 cup of granulated sugar, ¼ cup cocoa powder, 1 teaspoon baking soda, ½ teaspoon kosher salt, and the crushed chocolate sandwich cookies.

Make 3 wells in the dry ingredients with clean hands, then pour the following into each well: the 7 tablespoons of vegetable oil in one, the 1 tablespoon of white vinegar in another, and the 1 teaspoon of vanilla in the last.

Pour the 1 cup of cold water over the ingredients and whisk everything together until fully combined. If the mixture becomes too thick for the whisk, switch to a spatula. Be careful not to overmix.

Use an ice cream scoop to fill the cupcake tins three-quarters full, smoothing the tops with a small knife. You should have 12 regular-size cupcakes.

Bake at 350°F (175°C) for 25 minutes or until the cupcakes spring back when lightly touched or when a toothpick inserted comes out clean.

Allow the cupcakes to cool almost completely in the pan before attempting to remove them.

Once the cupcakes have cooled, create holes for the vanilla frosting filling.

If you have piping bags with tips, you can use them to make the holes. If not, gently press your thumb into the center of each cupcake, being careful not to go all the way to the bottom.

Fill a piping bag with a tip and about 1 cup of vanilla frosting. If you don’t have a piping bag, fill a zip-top bag with frosting and snip off a small corner.

Fill the holes in the cupcakes with the vanilla buttercream, filling them to the top.

If there is any excess vanilla frosting, return it to the bowl to use in the cookies and cream buttercream.

Make the Cookies and Cream Buttercream

Place the remaining 6 sandwich cookies in a zip-top bag and crush them with the flat side of a meat mallet or rolling pin until you have small crumbs (not as fine as the earlier sand-like consistency).

Gently fold the crumbs into the vanilla frosting using a spatula. Mix until just combined—be careful not to overmix, as this will make the frosting look muddy.

If you have piping bags, fill them with the cookies and cream frosting, using a wide tip such as Wilton 4B to prevent the crumbs from clogging the nozzle.

Pipe the cookies and cream frosting on top of each cupcake.

If you don't have piping bags, spread a thin layer of frosting on each cupcake.

If frosting by hand, chill the cupcakes in the fridge for 15 minutes to allow the thin layer to harden. This will help the frosting stay in place and prevent it from oozing out when you add more frosting.

If using a piping bag, this step is unnecessary.

Cut the remaining 6 chocolate sandwich cookies in half, saving the crumbs.

Sprinkle the crumbs on top of the frosted cupcakes and place one cookie half on each cupcake, if desired.